BAGHDAD, Iraq (AP) _ A surface-to-air missile left over from Saddam Hussein's regime fell off a trailer and exploded Sunday, killing three people and injuring at least two others, residents of a poor Baghdad neighborhood said.

They said the accident happened at about 10 a.m. in the al-Thawra slum as Iraqi contractors were removing four unexploded Iraqi missiles left over from the war.

Army Lt. Col. Joel Armstrong identified the rockets as SA2 surface-to-air-missiles. But he said he had no information on the explosion or the number of casualties. No U.S. soldier was involved in the destruction of the missiles, he said.

``We are really sorry for the victims,'' said Armstrong, 45, of Fort Polk, La.

Several cars, a car wash and two nearby car-repair shops were destroyed. Twisted metal and pieces of the missiles littered the area. U.S. soldiers brought fire engines and extinguished the fire, Armstrong said.

Unexploded ordnance from the war and ammunition caches are scattered throughout Iraq and are proving a major concern. Human rights groups have exhorted U.S. forces to clean up unexploded ordnance, particularly in populated areas. The Iraqi army hid much of its ammunition in schools.

Within minutes of hearing the explosions, an American patrol went to the area to investigate, Armstrong said.

Jasim al-Darraji, owner of a nearby car-repair shop, said workers had removed two missiles from the area and were moving another one. The missile was being placed on a trailer when it turned over, spewing yellow fluid.

Shortly afterward, it exploded. Fragments of it hit another missile that also exploded, causing deaths and destruction on the edge of al-Thawra City, a rough, predominantly Shiite area that was known until last month as Saddam City.

Seyed Abed-Mohammed al-Hamdani, who saw the explosion, said a teenage boy was killed in his car-repair shop as he waited for his father who was having his car fixed. Two of his employees were injured.

A young man riding in a bus was also was killed, as was a 13-year-old bystander, al-Hamdani said.

Armstrong said that, since Baghdad fell on April 9, his unit had destroyed 6,000 tons of ammunition caches in northeast Baghdad, where Thawra City is located.

In addition, it has blown up 203 pieces of unexploded ordnance in the same sector, including some unexploded American artillery.

``There are no more ammunitions in schools in northeast Baghdad,'' Armstrong said.