Two 18-wheelers collided in a fiery crash in pre-dawn hours on the northbound side of I-35W in Alvarado. One truck was carrying ethanol that bubbled the asphalt, causing an indefinite closure of the northbound lanes. (Candy McMIchen)

An accident involving two 18-wheeler trucks, one of them a tanker truck transporting ethanol, snarled traffic on both the south and northbound lanes of Interstate 35W just north of Alvarado Friday morning.

The tanker truck struck a guard rail on the northbound side of 35W around 4:30 a.m. The second truck hit the jackknifed tank truck starting the fire. The accident occurred near County Road 604 and the intersection of Highway 67.

Fire units from Alvarado, Burleson, Cleburne and Johnson Country responded to the fire. The fire was allowed to burn itself out before clearing the wreckage.

All northbound traffic must take Parkway Drive.

The northbound lane of the interstate will be closed indefinitely as the ethanol caused the asphalt to bubble and, according to the Texas Department of Transportation spokesperson, "will have to be replaced in sections."