Chattanooga, Tenn. (CNN) -- A sixth child has died from injuries sustained in a school bus crash in Chattanooga, Tennessee, police tweeted.

Kevin McClendon told CNN that his brother, Keyonte Wilson, "was a tough little boy."

"I know he's in a better place," McClendon said.

The bus was on its way home from school Monday when driver Johnthony Walker swerved off the road and the vehicle, with 37 students on board, plowed into a tree, according to officials.

Police Sgt. Austin Garrett said no traces of alcohol or drugs were found in Walker's blood.

The accident in which the bus flipped on its side was actually the second time in two months that Walker crashed a school bus.

Garrett said investigators had obtained warrants for all data devices on the bus and were reviewing video of front, back and side views of the vehicle.

In September, Walker was driving around a blind curve in a residential area when he failed to yield the right of way and sideswiped another car, according to the accident report.

In the earlier crash, which Garrett described as a "minor wreck," Walker "crossed over into the oncoming traffic lane to maneuver the bus through the curve and struck vehicle #2 in doing so," the report states. "There were no children in the front rows, and no reports of any injuries. The damage (was) minor to both vehicles."

Now, investigators are trying to determine why Walker was driving "well above" the speed limit when the bus hit a mailbox, a utility pole and flipped on its side as it struck a tree.

And as 11 children try to recover from the trauma -- some with severe head or spinal injuries -- the families of six children will have to spend their first Thanksgiving without them. Five victims remain hospitalized.

"We certainly understand on this week of Thanksgiving (that) we all need to be with our families, appreciating them, thinking about our kids, because there are a lot of families hurting in our city right now," Mayor Andy Berke told CNN on Wednesday.

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