PLACENTIA, Calif. (AP) _ A man whose botched robbery and false bomb threat left 29 people trapped in a bank for 6 1/2 hours on New Year's Eve acted alone, authorities said Wednesday.

Another man who authorities initially thought had taken part in the robbery was instead a fugitive who happened to be cashing a check at the bank.

The robber, Jaime Sabogal, 38, a native of Bogota, Colombia, killed himself after taking two bank employees hostage, commandeering a car and driving onto a nearby highway that was jammed with traffic.

Sabogal had said he left a satchel containing plastic explosives in the Bank of America branch and suggested he had an accomplice, Placentia police Lt. Chuck Babcock said. There turned out to be no bomb.

The 20 bank employees and nine customers were unharmed. Hundreds of spectators, friends and family members cheered and yelled ''Happy New Year 3/8'' as the group left the bank late Tuesday night.

They began leaving more than an hour after the man initially believed to be a second robber walked out.

Police later concluded the man, Gregory Robert Rambo, 30, of Los Angeles, wasn't involved in the robbery. He is wanted on felony larceny warrants issued in Dade County, Fla., and was being held at the Orange County Jail in Santa Ana, Babcock said.

Rambo, also known as Robert Charles Gregory, confused FBI agents and police outside the bank with his erratic behavior, delaying attempts to search for explosives and free those inside, authorities said.

Rambo talked to police by phone for several hours and moved about the bank, frightening those inside. Police kept an open phone line to the bank manager, who was with the others in a conference room.

''This guy was trying to be a hero. He put our lives in jeopardy,'' said Paige Sturgeon, a teller who remained in the bank. Others said the man appeared desperate to leave.

The drama began when the robber, wearing a gray suit, announced he had a bomb and displayed a gun, said Thomas Parker, assistant special agent with the Los Angeles FBI field office.

''This nicely dressed guy told us we were going to be robbed and told us the bomb had a motion-sensor,'' Sturgeon said. ''He also told us that the bomb was set to go off in one hour.''

Police responding to a silent alarm surrounded the building and watched as the man walked out with two women. He stopped a passing car, ordered a woman and her 13-year-old son to get out, and drove off with the hostages.

Police chased the robber onto a highway, where the car collided with three vehicles and got caught in traffic at an interchange, Babcock said. He ordered his hostages to get out of the car and shot himself in the head with a .45- caliber revolver, authorities said.

One of the hostages, Barbara Kelting, 36, was treated at a hospital for minor injuries, Brea Fire Capt. Dave Mahlstede said. The other woman was unhurt.

Police found money in the car, Babcock said, but authorities didn't immediately say how much.