BONN, JUNE 28 -- Three U.S. soldiers were killed and 12 were injured by an explosion today during a training exercise in West Germany, a U.S. Army spokesmen said.

The accident took place during a routine exercise at the Hohenfels training ground, the U.S. Army's largest training center in West Germany, 35 miles southeast of Nuremberg in the southeastern part of the country, the spokesmen said.

A 15-pound M180 cratering charge, used to make roads impassable, caused the deaths and injuries, said Lt. Col. Jake Dye, chief public affairs officer for the Army's 5th Corps. An investigative team from the U.S. Army Safety Center in Ft. Rucker, Ala., was on its way to West Germany to study the accident, he said.

"We don't know what happened, how or why," Dye said in a telephone interview from his office in Frankfurt. "This was fairly routine training for combat engineers."

The explosion was the latest in a series of accidents that have killed 12 men in military training exercises in recent months.

Ten national guardsmen were killed June 22 when an Army reserve UH1 helicopter crashed at Ft. Hood, Tex. Another soldier died the following night when a tank fired a dummy shell at two other tanks at the same base. On March 24, a 19-year-old soldier was drowned when the Bradley Fighting Vehicle in which he was riding plunged into a sinkhole on a training field in West Germany.

Today's accident was the most serious one suffered by U.S. Army personnel in this country since three soldiers were killed and 16 injured when a fire broke out on a Pershing II nuclear missile on Jan. 11, 1985, near Heilbronn, Lt. Col. Robert McDowell, acting chief spokesman for U.S. Army forces in Europe, said.

Apart from the Pershing missile accident, Army forces in Europe had suffered fatalities only in helicopter accidents in the past four years, McDowell said.

"We've been fortunate" in the recent past to have had no deaths from accidents during demolition training, McDowell said.

Most of the victims of today's accident were combat engineers of the 58th Combat Engineering Co. All of the victims were from the 11th Cavalry Regiment of the 5th Corps. Names of the victims were withheld pending notification of relatives.

A West German police spokesman in nearby Regensburg said that 30 soldiers had been injured, including 11 who were seriously hurt. West German police were the first to report the accident.

The two Army spokesmen said only that 12 soldiers had been hospitalized, and that they were unaware of any injuries that did not require hospitalization.

"I suspect that there were not any other injuries," Dye said.

The accident occurred at about 10 a.m. (4 a.m. EDT). Some of the injured were flown by helicopter to a civilian hospital in Erlangen and to one or more U.S. military hospitals in the Nuremberg area.

"Two soldiers were pronounced dead on arrival. Another died shortly after having been admitted to an area hospital," an Army statement said.

A spokesman for Erlangen's university hospital said some of the soldiers had lost limbs in the accident.

Dye said that initial reports indicated that the servicemen on the scene did a good job of caring for the injured after the accident.

"The unit immediately exercised procedures to get a large number of medics to the scene and to provide helicopters to get them out of there," Dye said. Washington Post staff writer Molly Moore contributed to this report.