Pakistanis have been voting in parliamentary and provincial elections that have been preceded by political violence and concerns about fraud.
BBC correspondents describe how the day developed.
Riaz Sohail, Tharparkar district, Sindh province, 1130 GMT
The entire district has been turned into a no-go area for Pakistan People's Party activists.
These PPP supporters in Tharparkar say they were stopped from voting
There were particularly strong reports of ballot boxes being stuffed by rival candidates in the sub district of Chachro.
When I went to check these reports I was fired on.
I joined at least 200 PPP supporters who had been repelled by the firing. At least five of them were injured. They said they had not been allowed to vote.
Abbas Naqvi, Karachi, 1130 GMT
In Karachi, protestors from the secular ANP party blocked roads and stoned vehicles after an attack on their candidate.
The ANP man was hit and injured after rival activists attacked his vehicle with firearms in the eastern part of the city. Later, the police and paramilitary rangers arrived and broke up the protest with a baton charge.
Polling was suspended in the area for half an hour.
Ali Salman, Daska district, Punjab, 1130 GMT
A PML-Q polling agent shot dead a rival PML-N polling agent after a dispute erupted between the two parties. Later, enraged PML-N workers set the house of the alleged assailant on fire.
Ali Salman, Gujranwala, Punjab, 1130 GMT
Firing on a polling station in the district led to the suspension of polling for half an hour. PML-Q activists allegedly attacked and injured two activists supporting an independent candidate.
Riffatullah Orakzai, Peshawar, NWFP, 1130 GMT
The northern city has so far been largely peaceful, no reports of any violence during elections so far. The turnout has been quite large, and if growing as the day progresses
Armain Sabir - Karachi, 1045 GMT
Voters at one polling station in Karachi east waited five hours for the polling to start.
Police stationed in Karachi
The presiding officer of the polling station told the BBC that police escorted him and his staff to a school where there was no polling station and which was five kilometres away from the actual polling station.
He said the police then departed, leaving them in the wrong place.
The presiding officer said polling was delayed for so long because it was difficult, given the lack of security, to get his staff and all the voting material to the correct place.
This polling station covers about 21,000 voters and is in a stronghold of the Pakistan People's Party.
Dilawar Khan, North West Frontier Province, 10:00 GMT
Nine security officers deployed to maintain order at polling stations have gone missing, feared kidnapped, near the town of Bannu, in North West Frontier Province, local police told the BBC Urdu service.
Jill McGivering, Karachi, 0900 GMT
Voting at a polling station in an affluent part of Karachi was delayed by half an hour. It couldn't start until polling agents signed off the ballot boxes and they failed to turn up. When it did start, there was only a trickle of voters.
Last minute preparations at a Karachi polling station
Some people couldn't work out where to vote, Others complained that their names had been missed off the voters' list.
One young man spent 90 minutes proving his right to vote. He said four of his family's names weren't on the list. Turnout stayed low all morning with some people put off by fears of violence.
The usually bustling city of Karachi is subdued. Shops are closed and streets are empty.
Barbara Plett, Lahore 06:50 GMT
Polling got off to a slow start. At the polling station in the centre of the city where I am, there's tight security. Outside a barrier is blocking off roads to prevent car bomb attacks.
A Lahore policemen on the eve of the vote
There has been some violence. Overnight gunmen opened fire on a provincial assembly candidate of the PML-N party of Nawaz Sharif. It's not clear if this was related to the elections or if it was a family feud although politics and family are often intertwined in Pakistan.
As for fears of rigging, there has been no evidence of irregularities here, but the local media are reporting suspicious activities in two constituencies in Lahore in one of which voting is said to have been suspended.
We are also getting reports that some people cannot find their names on the electoral roles.
Syed Shoaib Hasan, Rawalpindi, 06:45 GMT
Throughout the country there are separate polling stations for men and women. At one women's station in Rawalpindi, the office in charge, Shaista Tabbassum, said that of the 1,560 women eligible to vote there, some 150 votes had been cast by 1100 local time.
Men collect their ballot papers in a Rawalpindi voting station
One women, Guddo Bibi, said: "I have given my vote for Nawaz Sharif. There is fear but I think the security measures are good. All my family have come and they are also voting for the PML-N. The process has been quick."
The markets are generally closed down, traffic is light, cafes and roadside stalls are open. Turnout is getting heavier, most people in the four stations I have been to are voting for the opposition, that is, for Nawaz Sharif's PML-N party and the PPP that was led by Benazir Bhutto.
One of the main leaders of the party backing President Musharraf, the PML-Q, is former information minister Sheikh Rashid Ahmed. As he cast his vote, he told journalists that all was peaceful and that he thought PML-Q would win but there would be stiff competition.
Syed Shoaib Hasan, Rawalpindi, 05:49 GMT
I am outside the government Islamia Higher Secondary School which has been turned into a polling station in Rawalpindi.
Polling was delayed in some polling stations in the morning
The school is barely 500 yards from where Benazir Bhutto was assassinated on 27 December.
Many people have queued up to cast their ballots. My early impression is that turnout here is higher than in the 2002 elections.
The parties have installed stalls outside the school to help voters. There are no slogans being shouted, and no clashes. Voting is peaceful.
Voters in the queue say they are not afraid of violence, though there is a some concern.
One voter who I spoke to said he had turned out with his family to vote for the PPP.
He predicted a large turnout today, compared to the 2002 election.
M Ilyas Khan, Landhi, 05:12 GMT
I am in Landhi, a suburban industrial area outside Karachi with a mix of urban and rural voters. It's a predominantly Pashtun area.
People have risen early here and the place is abuzz with activity - hundreds of voters have been waiting around polling station to cast their ballots.
Security is tight at polling stations
But, outside at least one polling station I saw, there was some chaos.
Many voters told me that they had come at 0800 to cast their ballots, but polling had not begun.
Officials told me that the delay was due to the late arrival of the polling agents of various parties.
Election material - ballot papers, ink, etc. - has to be opened in the presence of these agents before voting can begin.
Polling at this booth began an hour late after the agents arrived.
The same problem happened in other areas. The political parties seem to taking a long time to send their agents to the polling stations.
I heard similar reports of delayed polling because of the late arrival of agents in Punjab.
We have just heard that a candidate in the neighbouring Malir district has been driven out a polling station by a rival candidate. I am on the way to Malir to check this claim.
M Ilyas Khan, Karachi, 04:10 GMT
I am travelling from Karachi to the neighbouring Malir district, about 20km (12 miles) away, to find out how polling is taking place in a predominantly rural constituency.
The city of Karachi anyway wakes up pretty late, and as I travelled through the city, I noticed very little activity.
There were very few people on the road. There were no voters visible in the polling booth. A few party workers could be seen in the candidates' offices outside polling stations.
I am headed for Malir district near Karachi. The district has a mix of rural and urban voters, with the majority of them living in farms. I hope to find more people casting their ballots there.