A Southeast Washington man was killed in a gasoline explosion yesterday as he attempted to warm up a bus that he drove for the Foundation Baptist Church on Sundays, District of Columbia fire officials reported.

Andrew Garner, 43, was pouring gasoline into the carburetor of the stalled bus when either engine heat or sparks from a fuel pump ignited gas fumes, said Murdo Macleay, a city fire inspector.

As the bus engine-located inside the bus under a rear seat-burned out of control, Garner yelled for Jan Owen, who was working the ignition key, to leave the bus and call firemen.

When she returned moments later, Garner was dead. A flash fire had gutted the bus.

"He was so dedicated to the bus he wouldn't leave it," Owen told Garner's relatives after the fire.

Garner, who lived at 1223 Valley Ave., SE., was chairman of the Trustee Board at the Foundation Baptist Church, located at 723 First St. NW. One of his tasks was to drive the 1968, 90-seat GMC bus, pick up members of the church who reside throughout the area, from Landover to Logan Circle.

Garner was also a supervisor at Efforts for Ex-Cons, a security guard company run by the Rev. Griffith Smith, pastor of Foundation Baptist.

"He rose from security guard to supervisor within a year because he was complete and dependable," Smith said yesterday. "Most men who start that far down are either complaining or late or not available when you need them for extra duty, but not brother Garner. He was always glad to do it."

Garner had joined the church four years ago, a few months after his daughter, Maria, 18, son, Reginald, 16, and daughter, Linda, 12 joined the church. His wife, Catherine, had already become a member.

"He changed because of his children," said Smith. "See, there was a time when his oldest daughter didn't believe in God, but she changed. So he thought time had come for him to change, too. It seemed like he wanted to be a part of where his children were and what they were doing."

Garner had come to Washington years ago from Garysburg, N.C., and had eventually settled into a fly-infested housing project in the far reaches of Southeast Washington.

Through the church, Smith said, Garner had built a "foundation for his life." He enjoyed his work as bus driver for the church and spent many Saturday mornings preparing the vehicle for Sunday duty.

The bus had been purchased four years ago from another church, said Smith, who had driven it before Garner was appointed trustee.

Fire inspector Macleay said the bus engine was old and emitted heavy fumes as Garner repeatedly poured in gasoline.

"In an old bus like that that just sits all week, the gas just seeps down to the bottom of the engine. He was trying to prime it like you would an old car in winter," Macleay said.

Within a few moments, the bus became a gas-filled box lined with leather and foam rubber seats.

"We all believe in heaven and hell," Smith said of his congregation yesterday. "And that God has power over all things, although sometimes He allows things to happen that disturbs us and makes us sorrowful. But He knows what He's doing and He teaches us to be prepared every day because you never know when the time might come." CAPTION: Picture, ANDREW GARNER . . . so dedicated he wouldn't leave bus