RADCLIFF, Ky. (AP) _ Authorities suspect that an equipment malfunction caused a leak of toxic gas at an underground sewer pump station, where a water district employee and three-would be rescuers were killed.

''It was a panic-type situation,'' said Marvin Logsdon, manager of Hardin County Water District No. 1, which operates the city sewer system. ''Each one trying to help the other.''

''There had to be a malfunction of some sort in the station,'' Logsdon said.

The men were probably killed by methane gas, officials said, but Hardin County Coroner Dr. James Stuteville said he had not ruled out drowning.

Methane gas is colorless, odorless and present in almost all sewers, Logsdon said. The 8-foot-square underground sewer station is ventilated and sealed to prevent a gas leak from the sewers, he said.

Radcliff Police Chief John Farrelly identified the victims as Rick DeRuiter, 28, Danny Cummings, 27, Raymond J. Dawley, 37, and police officer William Burns, 34.

DeRuiter and Cummings were doing a routine check at the station about 10 a.m. in the southern end of Radcliff, Farrelly said.

Officials said they believed that DeRuiter entered the shaft, developed breathing trouble and called to Cummings, who radioed for help and then entered the shaft.

Dawley, a water district supervisor, responded and went into the shaft to try to help the other two.

Burns and fellow officer Don Harris also responded, and Harris rescued Eric Meredith, a construction worker who had climbed into the shaft to help.

Burns went in and radioed for help, Farrelly said.

A volunteer firefighter, David Underdonk, put on an air pack and entered the shaft, but was overcome by the fumes. Underdonk, who weighs 240 pounds, became stuck in the shaft and rescuers had to pull him out with ropes.

He was taken to Hardin Memorial Hospital, treated and released.

Farrelly said rescuers delayed further attempts to reach the men because water had backed up into the station and covered them. Divers brought the bodies out.