An Illinois State Police trooper was killed early Saturday when a driver going the wrong way slammed into his squad car. The crash marks the third Illinois trooper death this year, and the second in just three days.

Trooper Gerald Ellis, 36, was referred to as "a great hero" by his colleagues. He was on duty and heading home in his squad car on Interstate 94 when a wrong-way driver hit his vehicle about 3:25 a.m.

Ellis, an 11-year State Police veteran, died at the hospital less than an hour later.

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Ellis was also a military veteran, and he leaves behind a wife and two children.

Illinois State Police Director Brendan Kelly called the loss "a bitter salt in an open wound."

On Thursday, Trooper Brooke Jones-Story was killed when a truck struck her in Freeport. In January, a vehicle hit Trooper Christopher Lambert near Northbrook.

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The fatalities come amid a sharp increase in drivers hitting squad cars that have stopped with their emergency lights on.

Saturday's death is the first time in 66 years that the Illinois State Police have lost three state troopers in one year.

The police issued a tweet Thursday, following Jones-Story’s death, with a photo of the highway’s overhead signs reading: “Enough Is Enough,” along with a notice on Scott’s Law.

Scott’s Law, also known as the “Move Over” Law, requires drivers to slow down and change lanes upon approaching “stationary authorized emergency” vehicles with their warning lights on, the Illinois State Police explained on their website.

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"There are only two ways this stops: People drive safely, or troopers stop patrolling,” Kelly said. "And there is nothing and no one on Earth, or in heaven or hell that will ever keep these troopers from doing the job that they swore to do.”

The Associated Press contributed to this report.