SANDY SPRINGS -- All lanes of Interstate 285, the top end Perimeter, have reopened following an early-morning tractor-trailer crash Thursday that prompted authorities to shut the busy freeway down for much of the morning rush hour commute.

The accident occurred shortly before 5 a.m. in the eastbound lanes of I-285 at the Ashford Dunwoody Road exit. The driver of the tractor-trailer was transported for treatment to a metro Atlanta hospital, where he was said to be listed in critical condition.

The driver of a pickup truck that slammed into the wrecked tractor trailer was also rushed to a metro Atlanta hospital, where he was suffering from critical injuries that were not believed to be life threatening. The identities of both drivers were pending.

Crews cleared the debris from the travel lanes and reopened the highway about 10 a.m., five hours after the wreck. Crews had suggested immediately after the accident that the freeway could be closed all day. All of the eastbound lanes were closed immediately after the accident and all but two westbound lanes.

Witnesses told police that the driver of the tractor-trailer, who is from Jacksonville, Fla., was driving erratically in the eastbound lanes of I-285 when the driver lost control of the vehicle. The big rig jackknifed, and the truck's cab slammed into a center concrete median wall.

Debris from that collision landed in the westbound lanes of I-285 and struck another car. The trailer, which was carrying automobile windshields, detached from the cab and came to a rest on the freeway.

The glass shattered and spilled onto the interstate along with a small amount of diesel fuel. The hazmat team was called to the scene.

"It just scattered debris everywhere," said Mark McKinnon, a spokesman for the state Department of Transportation. "We never know what a tractor-trailer is going to be hauling and when one flips over and loses its load, it's a challenge."

The pickup driver was unable to stop and slammed into the wrecked remains of the tractor-trailer. It was not immediately clear if the tractor-trailer driver would face charges in the wreck.

At one point, lanes in both travel directions were closed. A detour was established for motorists, many of whom were caught in gridlock for much of the morning commute.

Channel 2 Action News reporter Elenora Andrews and Mark Arum and Herb Emory in the Triple Team Traffic Center contributed to this report.