MANILA, Philippines (AP) _ Three passenger cars disconnected from a commuter train Monday and rolled backward for about a mile before colliding with another crowded train. Seven people died and 220 were injured.

Many people were crushed in a stampede as passengers of the Manila-bound trains tried to escape after the crash, witnesses said.

Some people were riding on the roof of the second train and were injured when they jumped off moments before the collision, said officials of Muntinlupa city, 30 miles south of Manila.

``Everybody was shouting and yelling in panic from the time our train got detached until we crashed,'' said Maria Villamin, a 44-year-old factory worker who was on the first train.

Reynaldo Recede, an operations officer for Philippine National Railways, said a coupler on the first train apparently failed, sending its three passenger coaches rolling backward about one mile before they hit the other train. One coach derailed in the collision with the five-coach second train, he said.

Witnesses said the wayward coaches bumped a passenger jeep and a van before smashing into the other train, injuring some people in the vehicles.

Jesus de Jesus, engineer of the second train, told reporters he tried to stop his train when the coaches suddenly appeared but it was too late.

The impact lifted one of the coaches off the tracks, causing it to tilt and scrape two shanties built close to the railway. The shanties were damaged but no one was hurt inside.

Josie Alba, who lives in one of the shanties, said some of the mangled bodies were thrown into her house. ``People, mostly bloodied, were falling off'' the derailed coach, she said.

Rush-hour traffic delayed the arrival of ambulances, and drivers of private cars passing near the accident helped many of the victims, officials said.

Police said an investigation was under way and officials of the state-run railway might be charged with criminal negligence.

Although Philippine railroads are old and generally in poor condition, many people still choose to ride them because of their cheaper fares.