A number of people have been killed in police raids in Haiti's capital, Port-au-Prince, after the government vowed to crack down on gangs.
Residents of Bel Air, Port-au-Prince, said police burned homes
Police said only two people died but witnesses said it could be nearer 20.
Officials had pledged a crackdown on gangs after Tuesday's killing of a French diplomat and an attack on a market that left 10 dead.
Haiti has been riven by violence since the ousting of President Jean-Bertrand Aristide last year.
Human rights groups say more than 600 people have been killed since last October.
There are about 7,400 UN peacekeeping troops trying to stabilise the country ahead of elections due before the end of the year.
US Secretary of State Condoleezza Rice said on Saturday more international troops might now be sent.
The police raids on Friday and Saturday targeted slum areas in the capital such as Bel Air, seen as strongholds of supporters of Mr Aristide, who is in exile in South Africa.
Police told the UN peacekeeping mission that two Aristide supporters had been killed and 35 people were being questioned, but they have refused to make any other comment on the raids.
Tuesday's market attack sparked the government raid on gangs
Morgue workers told Reuters news agency they had taken in 17 bodies on Saturday and three on Friday.
Witnesses accused the police of setting slum homes alight and shooting residents.
"The police arrived, they started shooting. There were other people shooting too, but they managed to flee," Bel Air resident Ronald Macillon told Reuters.
The AFP news agency reported seeing about 10 homes burned in Bel Air.
The police crackdown came in response to an attack on a market and a police station in the capital on Tuesday, in which 10 people died.
On the same day, the French honorary consul for the northern city of Cap-Haitien, Paul Henri Mourral, was shot dead in his car near Port-au-Prince airport.
Human rights groups have accused the police of summary executions of Aristide supporters - a charge the authorities deny.
Last week, the Brussels-based think tank, International Crisis Group, said Haiti was caught in a "deep political, social and economic crisis" with an "explosive" security situation.
On Saturday, Ms Rice said recent violence was "troubling".
"[We] need to look hard at whether or not the force posture there is adequate", she said. "It may be not just a matter of force posture. It may be a need for more election help."