SRI LANKA ? A bomb hidden on the baggage rack of a packed, rush-hour bus exploded Friday evening outside Colombo, killing 24 people in an attack that the military blamed on Tamil Tiger rebels.

Ambulances with sirens wailing flooded a nearby hospital, where off-duty doctors and nurses ran in to help the 40 people who were wounded in the blast. One hospital was so overwhelmed it had to divert some of the injured to a second medical center.

Among the dead brought to the morgue was a Buddhist monk and a small child.

The bomb exploded about 6:45 p.m. at the bus depot in the town of Piliyandala just south of the capital, sending pieces of seats flying, witnesses said.

The roof of the red public bus, which was about to depart for the nearby town of Kahapola, was torn apart and its windows – and those of nearby buildings – were shattered.

The bomb was hidden in a parcel on the overhead rack near the front of the bus, said a military spokesman, Brig. Udaya Nanayakkara, who blamed the Liberation Tigers of Tamil Eelam.