JEFFERSON CITY, Tenn. — A driver accused of running down a pregnant mother and her toddler son intentionally struck and killed them at random, authorities said.

William David Phillips, 33, faces two counts of first-degree murder and one count of attempted first-degree murder in connection with the vehicular rampage that left two people dead and two others wounded in Jefferson City on Monday afternoon, the Jefferson City Police Department announced in a news release Tuesday.

He is expected to be charged with another count of first-degree murder in connection with the death of the unborn child, the release states.

Police identified the pregnant mother as Sierra Wilson Cahoon, 30, and her son as 2-year-old Nolan. They were the wife and son of Matt Cahoon, an assistant athletic trainer at Carson-Newman University, a Christian school that sits less than a quarter-mile from where the crash occurred.

UPDATE:Warrants show driver claims voice told him to run down pregnant mother, son

'An intentional act of violence'

Investigators believe Phillips hopped behind the wheel of a Chevrolet Impala and drove west down East Main Street around 3:30 p.m. Monday, twice swerving onto the sidewalk to intentionally hit pedestrians, according to Jefferson City Police Department Capt. Darrell Turley.

Phillips first hit Tillman Gunter, 61, who was taken to a local hospital with injuries that didn't appear to be life-threatening.

Phillips then traveled less than a mile to the intersection of Russell Avenue and West Main Street, where he swerved to fatally strike Sierra and Nolan Cahoon, police said in a news release.

"The preliminary investigation has revealed that this was an intentional act of violence toward randomly chosen pedestrians," the release reads. "Investigators have determined that Phillips did not know the victims."

Phillips told authorities "a voice told him he needed to go kill meth addicts so he began driving very fast," arrest warrants state. "He said the voice told him that the baby stroller had meth in it so he intentionally drove into (the mother and child) ... killing them both."

Car crashed into fish hatchery

Phillips ultimately crashed the Impala into a nearby building on West Main Street that is owned by a fish hatchery called Sustainable Aquatics. Owner John Carberry said he arrived at the scene within minutes to find mother and child dead on the sidewalk.

"When I got there, there was a hole in the building, and one of my employees ran out," Carberry said. "She had minor injuries. She ran up to the main building, and the perpetrator ran out of the hole and ran up and some local citizens grabbed him."

Carberry said the car destroyed four fish systems as it entered the building, which is one of six owned by his company in the area. He estimated more than 10,000 gallons of water rushed from the tanks, along with thousands of wild-caught fish. Making matters worse, the crash knocked out power to the building, and Carberry could not access it until Tuesday since police had secured it as a crime scene.

Thousands of fish died, Carberry said.

"The car was going so fast that it went through a stop sign post and sent the stop sign post and sign over the building about 300 feet into the parking lot on the other side," he said. "It went through a guy wire holding a telephone pole. It went through a cinder-block wall. It went through a 6-by-6 stanchion, and then it went through a fish system that had 20 tons of water in it. It came to rest where the back bumper was 10 feet past the wall that it entered."

Carson-Newman mourns

Carson-Newman University interim President Paul Percy issued a statement Tuesday, saying the community is mourning the tragic loss of Sierra and Nolan Cahoon.

"Our hearts are breaking for one of our own," he said. "We take comfort in knowing that God also feels our pain and hears our prayers. Because of this, we ask for prayers for Matt and his family now and in the days ahead."

Carson-Newman Athletics Vice President Matt Pope also released a statement.

"We mourn the loss of two members of our Carson-Newman Athletics family," Pope said. "We send our deepest sympathies to the Cahoon and Wilson families and ask that everyone lift them up in prayer in this time of need. We grieve with Matt knowing that Christ will hear and, in time, assuage that grief."

The university has established a fund to benefit the Cahoon family. Those wishing to contribute may give online to "The Randall and Kay O'Brien Benevolent Fund" at www.cn.edu/cahoonfamilyfund. Donations may also be given by calling the university at 865-471-3233.

A GoFundMe page benefiting the family is also available at www.gofundme.com/funeral-fund-for-sierra-amp-nolan-cahoon.

Reach Travis Dorman at travis.dorman@knoxnews.com. Follow him on Twitter @travdorman.

Reach Brittany Crocker at brittany.crocker@knoxnews.com. Follow her on Twitter @brittcrocker.