MINNEAPOLIS (WCCO) – Minneapolis police are asking for the public’s help to find a driver who is throwing chunks of cement at bicyclists.

Twenty-year-old Mackenzie Jensen was seriously hurt when he was struck last week.

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Since June 20, police say five people have been attacked, four on bicycles and one in a car. All four bikers were injured, three of them seriously.

Police are now saying they believe all five attacks may be related. In each case the attacker is described as a white or Hispanic man in his 20s driving an older model white Ford, possibly a Bronco or a pickup with a topper.

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One of the rear windows is missing and covered with cardboard or wood.

Police say the suspect could be a construction worker, because one victim saw a yellow vest.

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If you have any information, call Crime Stoppers at 1-800-222-TIPS.