A rollover accident involving an 18-wheeler caused a major traffic backup on the northbound side of Interstate 35 in Salado, TxDOT confirmed with Channel 6 Tuesday afternoon.

TxDOT spokesperson Jodi Wheatley said the 18-wheeler was carrying concrete and estimated the cleanup would take between two and four hours.

Wheatley said the right lane was closed, but the left and center lane remained open.

Northbound Interstate 35 traffic cleared at approximately 3:33 p.m. Tuesday, according to Wheatley.