A 37-year-old transient suspected of throwing a hatchet at a group of people in a Bloomington, Indiana park kept police at bay for six hours by hiding in the maze of stormwater management sewers under the city, captured only after officers released a canine into the sewer to track him, NBC News reports.

Eli Swartzentruber, a homeless man with mental health issues who was reportedly living out of his car parked in a supermarket parking lot, was able to tolerate the flash-bang grenades and smoke bombs tossed down manholes and sewer grates as police tried to force him out.  The police also deployed robotic cameras in an effort to locate him.

From 11:30 a.m. Tuesday until 5:30 p.m., many neighborhoods in Bloomington, including parts of the campus of Indiana University, were told to shelter in place as police searched for Swartzentruber.  During the search, officers found a hand scythe, a machete and numerous rifle cartridges although they did not report finding a weapon. 

Police used a variety of devices to force Swartzentruber to travel to a specific point in the sewer systems, where he was seen on a utility service camera deployed to look for him.  Once they spotted him on a camera, they were able to conclusively identify him as the man responsible for the hatchet attack, because you never know how many men are wandering the sewers of Bloomington at any moment.  He ultimately surrendered when faced with a K-9 officer and his dog, Loki.