Canadian border guards discovered a package containing 22 kilograms of heroin at Pearson International Airport last week.

The package was offloaded from a flight arriving from Pakistan, the Canada Border Services Agency said Monday.

According to the CBSA, the drugs were discovered on Oct. 30 after border inspectors noticed a box that had been obviously tampered with.

Upon opening the package, officers found a number of solid packages inside the box that tested positive for heroin.

“This significant seizure speaks to the vigilance and expertise of our officers at our ports of entry,” Goran Vragovic, of the CBSA, said in a press release.

“In preventing the smuggling of deadly narcotics such as heroin, border services officers are a crucial first step in stopping these drugs from making it to our streets and corrupting the safety of our communities.”

Peel police are currently investigating.

To date this year, CBSA officers working at GTA airports have seized over 106 kilograms of heroin worth an estimated $42 million.