PITTSBURGH -- Logan Cooley completed a hat trick against his hometown team with a second left, Mikhail Sergachev scored at 3:27 of overtime, and the Utah Mammoth stunned the Pittsburgh Penguins 4-3 on Thursday night.
After Ben Kindel put the Penguins ahead 3-2 with 25 seconds left, Cooley -- playing his third NHL game in Pittsburgh -- batted the puck in from the left side of the net for sixth goal in four games and seventh of the season.
Cooley became the third Pittsburgh native with a hat trick against the Penguins, joining Brandon Saad and R.J. Umberger. At age 5, Cooley took part in Sidney Crosby's first Little Penguins Learn to Play Hockey program.
Cooley scored for the first time in seven games against Pittsburgh. He had two first-period goals to give the Mammoth an early 2-0 lead and scored in the third for his third career hat trick.
In overtime, Sergachev beat Arturs Silovs off a rebound in front.
Sebastian Cossa stopped 31 shots for the Mammoth, who have won three of their past five games. Utah is 5-0-0 after a loss and 8-0-0 when leading after two periods.
Rickard Rakell had a short-handed goal, and Erik Karlsson also scored for Pittsburgh. Silovs made 30 saves.
It was the 10th game in NHL history (including playoffs) where opposing teams exchanged either a go-ahead or game-tying goal in the final 30 seconds of regulation, and the first since April 7, 2015 (New York Islanders at Philadelphia Flyers).
ESPN Research and The Associated Press contributed to this report.