The Massachusetts State Police is investigating a piece of military ordinance in an effort that has closed the west side of the Mystic Valley Parkway.

The MSP reports that its bomb squad as well as the Medford Fire Department are on scene at the Condon Shell, a Medford park, and investigating military ordinance found at the park. The piece appears to be a defused mortar based on the photos shared by the MSP on X, formerly known as Twitter.

Authorities said at around 2:30 p.m. Saturday that the west side of the stretch of Route 16 known as the Mystic Valley Parkway is closed between Main Street and Winthrop Street as the possible explosive is being investigated.

This is a developing story.