Does anyone know the. Cause of all the police activity at the southern end of the Northern Strand trail this morning?

There was a heavy police presence on the southern mile of the Northern Strand this morning, behind the Costco/Home depot. Between Encore and the wooden bridge over the marshland, I passed 4 groups of Everett police. 2 groups were on foot and 2 had golf cart like vehicles. They were not stopping or even interacting with cyclists or runners, so it couldn't have been anything immediately dangerous.

Anyone know what this was about? I've done that section hundreds of times and never seen one cop so this many definitely means something was up.