The pilot and two passengers of a single-engine airplane were killed last night when the plane crashed into the quiet surburban neighborhood of Riverdale Heights, exploding in fire in the front yard of a house shortly after taking off from College Park Airport, authorities said.

Maryland State Police identified two of the deceased early this morning as brothers Louis William Santacroge, 25, of Forestville, and John Dennis Santacroge, 37, of Arnold, Md.

The third victim, Ralph J. Sansone, 32, of New York, was believed to be a brother-in-law of the Santacroges, police said.

They said it was impossible to determine which of the men had piloted the plane because of the position of the bodies in the cabin after the crash.

Prince George's County Fire Department spokesman Tony DeStefano said the airplane crashed shortly before 7:25 p.m. in front of a green, aluminum-sided house at 6005 Sarvis Ave.

Five persons live in the house, DeStefano said, and three were inside at the time of the crash.

Besides the fatalities, no injuries were reported.

DeStefano said county fire units "responded immediately to what we saw as a column of smoke" from the airport grounds, about a half-mile from the crash site, where firefighters were taking part in a festival and demonstration.

John Barney, the airport manager, said the brown and beige Bellanca Viking had landed at the airport with three adults aboard.

The three bought 40 gallons of fuel, he said, and the airplane was not moved from the runway. When the refueling was completed, the light plane took off on the same runway, Barney said. He said he did not notice anything unusual about the plane.

DeStefano said there appeared to be nothing abnormal about the incident, but that the cause, which was unknown, would be investigated by the National Transportation Safety Board and the Maryland State Police.

Police said early this morning that there was speculation that the men had flown into College Park from Myrtle Beach, S.C. But the plane's origin was unconfirmed, they said, and its destination unknown.

They said preliminary indications were that the plane may have experienced fuel line problems, but that theory has not been confirmed and the cause is officially undetermined.

DeStefano said firefighters were able to douse the flames within minutes of arriving at the scene, where the airplane came to rest with its nose pointing away from the green frame house toward the tree-lined street.

Mark Snider, who lives at 6005, refused comment on the incident other than to say that the house was "scorched a bit."

"You could tell it was out of control," said Tom Carey, 16, a neighborhood resident who saw the crash.

Carey stood with a growing number of neighbors and onlookers who gathered to view the charred skeleton of the aircraft.

Carey said he was walking toward the house when he first spotted the airplane. "It was above the house and it was out of control up in the air." He said he heard engine noise and saw the airplane's tail swing around.

After hitting a pine tree, the airplane nosedived into a tarpaulin-covered shrub in front of the house, slid off the tarpaulin and its tail swung around as the plane hit the ground.

Bobby Brasted, 17, who lives two doors from the crash site, said he was inside his house and heard a "boom.

"It sounded like thunder or something," he said. "It jolted the whole ground." His father ran outside, he said, yelled that there was a plane crash, and his mother telephoned authorities.

"It didn't blow up until five minutes after it crashed," Brasted said.

Carey said one man in the front right side of the cabin was bleeding from the neck and arm and moving when the airplane first went down. "I ran right next to it and it was in perfect shape when it landed," he said.

He said someone yelled that the airplane would explode, and just after the warning, a small part of the airplane caught fire, and shortly afterward the craft was engulfed in a fire ball.

A man who lives in the house where the plane crashed came running out when the plane went down, Carey said, but "once it went up [in flames] he knew the guy was going to die. The concern was for the house and the people around."

The man was attempting to fight the flames with a garden hose at the time firefighters arrived, Carey said.

William Wagner, who lives across the street from the crash site at 6000 Sarvis Ave., said that after hearing the impact from inside his house he walked up to a spot in front of the house.

"I saw the pilot. The pilot and the copilot were dead, apparently. And the person in the back looked alive," Wagner said. "I was standing there. All of a sudden, I heard a voice say, 'It's going to blow.' Ten seconds later it blew.

"It was sad, I'll tell you that."

"How can you divert an airplane from crashing?" asked Lanham resident Bill Argy, 35. "You either don't have airports or you don't have houses."

Mona Ford, 35, a Riverdale resident, was leaving the firefighting demonstration at the airport with her two children and a neighbor's son when she was "almost pushed off the road by an ambulance rushing to the scene.

She said she followed the ambulance to the site because a friend works on Sarvis Avenue and Ford was worried for the friend's safety.

But when Ford found out there was a plane crash, she was more worried, she said, because her husband, who does some flying, had stayed behind at the airport.