A smash-and-grab jewelry robbery left two men dead after a highway gun battle and a high-speed police chase that started at a suburban shopping mall near London, Ontario, on Wednesday, the Canadian Broadcasting Corp. reports.

Dozens of police cruisers and a heavily-armed SWAT team swooped down on the crash site on Highway 402 where police had been chasing a luxury sport utility vehicle before it finally crashed following a 20-minute pursuit, CBC reports.

Ontario’s police watchdog agency, the Special Investigation Unit, is probing the incident that involved up to 50 police cruisers and several helicopters, CBC reports. The arms-length SIU is called in to investigate all civilian deaths involving police.

The SIU said one man died at the scene, while three others were seriously injured, CBC reports. One of the injured men later died in hospital.

A spokeswoman for the agency confirmed shots were fired during the chase, but wouldn’t say if police had discharged their weapons, nor would she comment how the two men died, CBC reports. The crashed vehicle was earlier seen racing down a street in London with a gunman inside the vehicle waving a weapon.

“The guy was hanging out of the sun roof holding a gun,” a witness told CBC.

London police said two officers were treated for minor injuries, CBC reports. The pursuit began just before 2 p.m., when sledge hammer-wielding bandits smashed display cases at a jewelry store in a mall and fled with an undisclosed amount of loot.

Police reportedly said they had an undisclosed number of people in custody and were no longer seeking suspects.

There were no reports of customers or store employees hurt in the robbery and chase, CBC reports. Part of Ontario highway 402 was shut down for several hours.

JCK