Three Thai policemen have been killed in a bomb explosion in the country's restive south.
A rubber factory was set on fire during a night of attacks
The officers were inspecting railway tracks in Chana district in Songkhla province when the explosion occurred.
The attack is the latest in a string of violent incidents in the Thai south, where more than 1,300 people have been killed since January 2004.
Officials blame Muslim insurgents for much of the unrest, although criminals are also thought to be at work.
In Wednesday's incident, a bomb placed near a bridge was detonated as a car of four policemen passed by. Three of the officers died instantly and the other was wounded.
Electrical wire was later found leading from the tracks to bushes about 100m away.
The southern provinces are predominantly Muslim, with a language and culture separate from the rest of Thailand.
The bombing took place after a night of apparently co-ordinated arson, bombing and shooting attacks in the three Thai provinces with Muslim majorities, Yala, Narathiwat and Pattani.
Home to most of Thailand's 4% Muslim minority
Muslim rebels fought the government up to the mid-80s
Suspected militants have upped attacks since 2004, targeting Buddhists
Security forces' response criticised by rights groups
Police booths and a rubber factory were set on fire and small bombs exploded outside karaoke bars, officials said.
In Narathiwat, Thai journalists reported that Molotov cocktails had been thrown at a Buddhist temple, soldiers had been drawn into a gun battle, and rifles had been fired at the homes of police and teachers.
No one was killed in the attacks.
Despite a heavy Thai security presence in the region, attacks such as drive-by shootings or small bombings take place almost daily.