Armed thieves ambushed a private plane as it taxied down the tarmac Saturday and fled with nearly $13.7 million in gold ingots and other valuables in one of Canada's largest robberies, police said.

The pre-dawn heist at Dorval International Airport outside Montreal was carried out with commando-style precision by at least four men, including one armed with a Soviet-made AK47 assault rifle.They used a stolen garbage truck to smash through a fence, then drove off with the loot in stolen vans, police said. A pipe bomb exploded three miles away under an airport construction trailer, and police called it a "diversion tactic."

The vans and the weapon were later found about 31/2 miles from the airport.

"It was well-executed," said Detective Lt. Allen Trepanier, a Montreal police spokesman. "For sure, this was done by an organized group."

The twin-engined turbojet, owned by Sky Services Inc. of Montreal, had been chartered by Brink's Canada Ltd. and was returning from a regular overnight run from New York via Ottawa and Toronto. It landed shortly before 4 a.m. EST and ran straight into the ambush.

"As it was taxiing up to the hangar, a heavy garbage truck broke through a fence followed by two Econoline vans that moved into position to block the front and rear of the craft," said police spokesman Lt. Andrew Theodosis.

A masked thief carrying the AK47 stayed on the ground while three others went inside the plane, Theodosis said.

"They told the three people aboard - a Brink's guard, the pilot and the co-pilot - to keep looking straight ahead, not to turn back. Then they started unloading the cargo area," he said.

The crew or guard could not give police a detailed description of the robbers, who spoke English and French.

Theodosis said the men drove away with gold and silver ingots, bonds, securities and jewelry. However, they left behind sacks containing an unspecified amount of cash.

Police said no one was injured and no shots fired.

"Prints were found," Trepanier said. "That's all we can say at this point."

A Brink's official in Montreal refused to comment on the case and said all information will be released by the firm's headquarters in Darien, Conn.