PUERTO VALLARTA, Mexico — Two Canadian men were shot to death in execution-style slayings outside an apartment building in the Mexican resort of Puerto Vallarta, authorities said Monday.

Witnesses told police that a gunman approached Gordon Douglas Kendall and Jeffrey Ronald Ivans outside the building they were staying in and shot Kendall, according to Jalisco state prosecutor Guillermo Diaz.

The gunman then chased Ivans to the pool area and shot him. Witnesses said two other gunmen arrived minutes later and repeatedly shot the dead or dying Canadians, Diaz said. The men fled and no arrests have been made.

Diaz said Ivans was carrying a handgun, though he apparently was not able to use it before he was shot. It is unusual for people in Mexico, particularly foreigners, to carry handguns. It was not clear if Ivans had a permit.

Diaz said police have reports that the men were involved in real estate developments in another nearby resort area, Bahia de Banderas.

Investigators have not determined a motive for the killing.

Sgt. Bill Whalen of the Royal Canadian Mounted Police said the service’s organized crime and gang units suspected Kendall and Ivans of being in the drug trade in the Canadian province of British Columbia.

“We were aware of who they were, that they were in Mexico and that they were involved in the drug trade,” said Whalen, an officer in the RCMP’s Combined Forces Special Enforcment Unit.