A large explosion has struck Sri Lanka's capital, Colombo, reported BBC.
At least 43 people have been wounded and are being treated in hospitals, the Sri Lankan military said.
The blast comes as the government is undertaking a large offensive against Tamil Tiger rebels in northern areas of Sri Lanka.
Tens of thousands of people have fled their homes in Kilinochchi district as the military has rapidly advanced into Tiger territory.
The BBC's Roland Buerk in Colombo says the military has reported that this was a bomb and the work of the Tamil Tigers.
The blast took place on what would normally be a busy Saturday lunchtime in a market area near the main bus station, our correspondent says.
There has been no claim of responsibility so far.
A hospital spokeswoman told AFP news agency three of the wounded were in serious condition.
The Tamil Tigers have been fighting for a separate homeland in the north and east for 25 years. More than 70,000 people have died.
The government has blamed the rebels for a string of bomb attacks on public targets amid the offensive in the north.