A U.S.-Canadian "sting" of suspected cross-border gunrunners uncovered a massive arsenal of machine guns, bazookas, grenades, dynamite and plastic explosives, Canadian and U.S. officials said Saturday.

Four men and one woman, all Canadians ranging in age from 28 to 36, were arrested in Friday night raids of five residences and a business in the Montreal area, said U.S. Customs Service Special Agent John O'Hara, who initiated the international investigation from his outpost at Rouses Point, N.Y., on the Canadian border.One of the suspects, Regent Myre, was believed to be the kingpin of what Canadian authorities called a major weapons smuggling ring, O'Hara said. The other suspects were identified as Jean Fauvel, Carol DesRosiers and Maurice Richard. The woman's name was not given.

"It seems to be an international organization," said Montreal Police Constable Serge St. Laurent. "They were bringing the weapons into Quebec and sending them into the United States."

The investigation began several months ago when undercover U.S. Customs agents in Plattsburgh, N.Y., contacted Fauvel, a suspected Canadian gunrunner, and agreed to purchase two Israeli-made Uzi 9mm machine pistols for $10,000, O'Hara said.

Canadian authorities immediately were notified and Fauvel's Montreal home was put under surveillance.

Undercover U.S. agents won Fau-vel's trust with a story that they needed weapons for "Central America" and agreed to buy 20 more Uzis.