SAARBRUECKEN, West Germany (AP) _ An express passenger train today slammed into a derailed freight train in southern West Germany, and officials said one person was killed and at least eight seriously injured.

Egon Thewes, a spokesman for the federal railway office in Saarbruecken said the passenger train hit the cars of a freight train that derailed after heavy rains washed debris and mud on railroad tracks east of Kaiserslautern.

Kaiserslautern is located about 90 miles southwest of Frankfurt.

Rescue workers found one person killed in the accident and at least eight seriously injured, officials said. The injured were taken to hospitals in the area, Thewes said.

More than 100 people were on the passenger train when the accident occurred, officials said.

Thewes said the accident occurred on just east of Kaiserslautern when the freight train plowed into a mudslide caused by heavy showers in the area.

The freight train derailed after crashing into the debris from the mudslide, with some cars blocking parallel tracks, officials said.

''The express train plowed into this mass of derailed cars and mud and all of its cars left the track,'' said Thewes.

He said the freight train was headed for Mannheim with a load of coal. The passenger train was going from Heidelberg to Saarbruecken, Thewes said.

Thewes said heavy cranes were being used to clear the tracks of damaged railroad cars.