SAN SALVADOR, El Salvador--A strong earthquake and aftershocks wrecked buildings in downtown San Salvador yesterday, and unconfirmed reports said scores of people had been killed.

Radio station YSU said more than 150 people had been killed in the collapse of the 10-story Ruben Dario building. Another report, by Radio Cuscatlan, said 30 people, mostly children, died in the Santa Catalina building. Neither report could be confirmed immediately.

Some downtown buildings were reduced to bent and twisted steel, and officials warned other building in this city of 500,000 people might collapse later.

The U.S. Geological Survey said an earthquake measuring 5.4 on the Richter scale, centered about 10 miles northwest of San Salvador, struck at 1:40 p.m. EDT, 11:40 a.m., Salvadoran time. At least seven or eight aftershocks were felt in San Salvador over the next three hours.

According to the Guatemalan Seismological Station in Guatemala City, a second tremor registered 4.5 and struck at 2:04 p.m.

Volunteers were working in the downtown section to dig out victims trapped in a store when a five-story building collapsed.

Some downtown high-rise buildings had sunk into the ground, and shards of glass were hanging from office buildings. Streets were strewn with downed power lines and broken glass.

Shanties of corrugated steel and wood collapsed in nearby slum areas, but wealthy neighborhoods in the hills appeared not to have suffered damage.

Radio Cuscatlan reported some looting.

An official from the Salvadoran Health Ministry told the radio many injured were being admitted to local hospitals. He made an urgent call for doctors and nurses to report immediately.

Vacationing Americans Robert Annadle and his wife Pam Ascanio, who were inside a pizza parlor when the initial jolt hit, said the tremor damaged Bloom Children's Hospital across the street.

They were digging out (from the hospital) kids, babies," said Ms. Ascania, of Rockledge, Fla.. "I helped carry a dead baby."