At least 21 people were injured Sunday in a series of car crashes that involved at least 130 vehicles and shut down part of Interstate 40 in North Carolina, authorities said.

The Alamance County Sheriff's Office told WRAL-TV that nine separate accidents occurred between Exits 147 and 153 Sunday night. 

Sgt. Danny Jenkins told The Times-News of Burlington that as many as 134 vehicles were involved in the wrecks that began late Sunday afternoon over a six-mile stretch of the highway between Mebane and Graham.

North Carolina Highway Patrol spokesman Jordan Pack told the News & Observer of Raleigh that investigators were not sure what caused the initial accident. However, WRAL reported that wet conditions may have been a contributing factor in many of the accidents, while rubbernecking could have caused several others.

Authorities said 21 people were taken to local hospitals. None of the injuries were believed to be life-threatening. 

WTVD-TV reported that seven accidents took place on the westbound side of Interstate 40, with two others occurring on the eastbound side. 

The North Carolina Department of Transportation confirmed around 8:45 p.m. that I-40 West/I-85 South was closed at an exit near Burlington, about 20 miles east of Greensboro. It reopened around 11:15 p.m.