COLOMBO, Sri Lanka (AP) _ Immediately after the explosion at Colombo's main bus station Tuesday, there was the expected chaos.

Ambulances, private cars and even buses were pressed into service to move the dead and wounded to hospitals.

Among the victims of the attack, blamed on Tamil militants, were people trapped in passenger buses and burned to death. Others survived with bruises and broken limbs from the panic stampede the blast set off.

The scene was made more grisly by rainfall, which mixed mud with the blood on the crowded streets of Sri Lanka's capital.

Members of the army and navy moved in immediately to try to control the situation. There was shouting and anger but no shooting, for the crowd was more tense than the military.

Soldiers quickly cordoned off the area to help rescue efforts, hampered by the rain and the glass shards from broken windows.

Tamil militants have been fighting a nearly four-year war with the Sinhalese-dominated government to demand that their minority people be granted a separate homeland in Sri Lanka's north and east, where most Tamils live.

Tamils, who are mostly Hindus, make up 18 percent of the country's 16 million population. Sinhalese Buddhists are nearly 75 percent and control the government and military. The rest are Moslems and descendants of European colonial settlers.

The explosion Tuesday, which killed up to 150 people and injured 200 others, followed two massacres blamed on Tamil militants in the last four days. Both occurred in the troubled eastern Trincomalee District.

As word of the bombing spread, people gathered in small knots on downtown streets to discuss the latest turn in the ethnic civil war that has enveloped their tiny island nation.

But anger did not seem to be so much aimed at the Tamils as at the government.

One Sinhalese man, who would give only his first name, Mohinda, was asked about the situation and replied: ''The bastards.''

But as he explained his views, it became clear he was referring to politicians and not to Tamils.

''Tamils and Sinhalese marry, they live together,'' He said. ''This is not a living problem. It is politics.''

Mohinda said it was not only the government but also Tamil politicians who caused the problem on the island. ''If the law treated everyone the same, there would be no problem,'' he said.

The Tamils complain of discrimination against their Tamil language and in education and jobs.

Mohinda may not be typical.

There were reports that some Sinhalese youths were roaming the streets of Colombo on Tuesday night, stopping cars and asking whether occupants were Sinhalese or Tamil.

At least three shops owned by Tamils in the capital were stoned by mobs of Sinhalese, but they were dispersed by police.

The government stepped in quickly to impose a curfew starting at 8 p.m. and extending to 5 a.m. Wednesday. It ordered all banks, businesses and government offices to close Wednesday.

The government said people would be allowed on the streets for four hours starting at 5 a.m. to shop for necessities, but the curfew then would be reimposed.

While the Tamil conflict has largely enveloped the north and east of the country, Colombo has not been untouched.

In July of 1983, with the first major attack by Tamil separatists on the army, rioting erupted in Colombo and surrounding areas. Official figures put the death toll from those riots at 400, most of them Tamils. But it is believed that the figure may be as high as 2,000.

Many Sri Lankans, even Sinhalese, charge that the government and military encouraged the anti-Tamil violence.

The curfew imposed in Colombo on Tuesday night appeared to be more stringent than any in the past. There was virtually no one on the streets but soldiers and police.

From doorways, people peeked hesitantly out to see what was happening. But few ventured out.