Police arrested a driver accused of intentionally running over pedestrians in Tennessee, killing a pregnant mother and her toddler son.

The Knoxville News Sentinel reports Jefferson City police say 33-year-old William David Phillips struck and killed the pedestrians at random Monday afternoon. Authorities identified the dead victims as 30-year-old Sierra Wilson Cahoon, who was pregnant, and her 2-year-old son Nolan.

Investigators say Phillips first hit 61-year-old Tillman Gunter. He suffered minor injuries.

Then, police say Phillips drove onto the sidewalk, struck the Cahoons and crashed into a fish hatchery. John Carberry owns Sustainable Aquatics and says thousands of fish died and more than 10,000 gallons (37,800 liters) of water spilled from the building. He says one employee suffered minor cuts.

It's unclear whether Phillips had an attorney who could comment.

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Information from: Knoxville News Sentinel, http://www.knoxnews.com