CHICAGO (CBS) — A northwest Indiana sheriff’s officer has been charged with drunk driving, after seriously injuring a man in a hit-and-run crash Sunday evening.

Police said Lake County Sheriff’s Department Lt. Guy Mikulich had a blood alcohol level nearly twice the legal limit at the time of the crash in Gary, Indiana.

OFFICIALS: Investigating whether Lt. was drinking all day, on-duty, at air show on Miller Beach. @cbschicago pic.twitter.com/96B3pH1Z1q — Brad Edwards (@tvbrad) July 11, 2016

Investigators are now looking into whether Mikulich was drinking all day, while on duty, at the Gary Air Show.

Witnesses said a father packing up his van with his family was struck at the corner of Pike Street and Oak Avenue around 4:50 p.m. The impact sent the victim flying.

Home surveillance video provided exclusively to CBS 2 shows the victim standing behind his van, when a black Ford Crown Victoria struck him from behind.

“I was on my patio, and I heard the thud, and I heard her start screaming, and I ran out,” neighbor Jim Corbeille said.

Corbeille said spectators were leaving the Gary Air Show at Miller Beach at the time, and had parked nearby.

Derrick Dircks, a 34-year-old resident of Frankfort, Illinois, was one of them, and was packing up his van with his family when Mikulich allegedly struck him. Police said Mikulich was still in uniform, driving his unmarked squad car.

Police said Mikulich kept going as Dircks laid on the ground. Dircks was taken to Methodist Hospitals Northlake Campus in Gary with serious injuries. Officials said his van was parked legally.

Corbeille said he tried to help Dircks after the man was hit.

“You feel so helpless. You’re down there trying to help the man, and his wife is just hysterical. He wasn’t really moving much, and I couldn’t even tell if he was breathing,” he said. “I tried to straighten out his legs just a little bit, see if anything was broken, and everything seemed to be okay in his arms, and then he just had his one eye opened up.”

Corbeille had seen Dircks and his family at the air show earlier in the day.

“They sat right in front of us down at the beach, and I mean the greatest, cutest little family. They had five children – four girls and a boy – and they were just having a great time, and for this to happen is just, for them, it’s sad,” he said.

Mikulich, 37, is a 16-year veteran of the Lake County Sheriff’s Department. He had been working the air show minutes before the crash. Police said Mikulich was arrested a short time after hitting Dircks, and had a blood alcohol content of 0.15, almost twice the legal limit of 0.08.

“That really surprised me, that they wouldn’t stop, and then of course finding out this morning that had been drinking,” Corbeille said.

Mikulich was being held at the Lake County Jail, charged with two felonies – operating a vehicle while intoxicated and causing bodily injury and leaving the scene of a crash involving an injured person.

The lieutenant has been in trouble before. In 2009, the county settled a lawsuit filed by a man who claimed Mikulich beat him in 2006.

Mikulich has been placed on paid administrative leave.