“The Peace Arch border crossing was closed for four hours Sunday night after a Lower Mainland woman threatened to detonate a “suspicious object” in her bag, RCMP said.

The woman attempted to enter the U.S. at the crossing but was turned back by American border authorities, Surrey RCMP Insp. Derren Lench told CBC News Monday.

After returning to the Canadian side, the woman, in her 30s, claimed she had a “suspicious object” in her bag, Lench said.

The crossing was shut down while the RCMP explosives disposal unit isolated the bag for examination.

Lench said the object turned out not to be an explosive device.

“It was just a large metal cylinder similar to a CO2 cartridge, but a large one that might be in a soft drink machine,” Lench said in a telephone interview Monday.

“Based on her disclosure and the need to treat everything in a real fashion we felt it was necessary to treat it that way.”

The woman, who has not been identified, was taken to hospital to undergo psychiatric testing, Lench said.

The Peace Arch border crossing reopened at 12:40 a.m. Monday.”