A trespassing investigation at Western University that led to the discovery of bomb-making chemicals has stretched to Ottawa and Gatineau, police say.

London police remain near Chesham Avenue and Chesham Place more than a week after responding to a call for trespassing at the school.

Around 1:40 a.m. on Jan. 24, London police officers were called to assist the Western University Special Constable Service regarding a trespasser in custody. Police said in a news release the special constables arrested a man after a foot pursuit on campus; officers also found a loaded handgun at the scene of the arrest.

Investigators determined a second man had been involved in the trespassing incident and eventually went to a residence near Chesham Avenue and Chesham Place. There, officers found hazardous chemicals capable of being used to create explosives, leading to the arrest of two additional individuals connected to the home.

Explosive disposal technicians secured the home, and it has been under police guard since.

Get breaking National news

For news impacting Canada and around the world, sign up for breaking news alerts delivered directly to you when they happen.

Since the initial incident, investigators have expanded their probe and executed search warrants in Ottawa and Gatineau, Que.

“This complex investigation has spanned multiple cities and provinces. We are grateful for the collaboration and support of our law enforcement partners,” the force said in a Jan. 30 news release.

Police said Monday its officers remain on scene and are removing equipment; partner agencies are also leaving the scene, it added.

A 27-year-old man from Ottawa and a 26-year-old man from London have been charged with multiple offences, including firearm-related charges, resisting arrest, break and enter with intent and occupying a motor vehicle with a firearm.

A 25-year-old man and a 21-year-old man, both from London, have also been charged with unlawful possession of explosives.

Western University told Global News in a statement last week it’s “working closely with the London Police Service on this investigation.”

“Our top priority is the safety of our campus community, and we have assurance from LPS that the buildings involved in the weekend incident are secure and safe,” it added.

Anyone with information is asked to contact police.

— With files from Global News’ Prisha Dev

&copy 2026 Global News, a division of Corus Entertainment Inc.