Toxic chemical spill closes Atlanta freeway Officials said the interstate should remain closed for at least 6 hours.

 -- A toxic chemical spill caused by an overturned tractor-trailer partially shut down a major highway in Atlanta early Monday.

The accident took place at around 3:34 a.m. near 10th Street on Atlanta's Downtown Connector, a stretch of road where two interstate highways, I-75 and I-85, run side-by-side for several miles.

After initially halting traffic in both directions, officials in Atlanta reopened the southbound lanes at around 6:30 a.m. this morning and expect to have the remaining lanes free by 10 a.m.

Police did not disclose the chemical that was released from the overturned vehicle.

Hazmat crews were at the scene in the predawn hours and police said that no one was allowed to come within 150 yards of the site of the spill.

A spokesman for the Atlanta Police Department told ABC News that officials expect traffic to be significantly impacted, with commuters facing 1-2 hour delays.

ABC News' Rachel Katz contributed to this story.