Update, 9:50 a.m.
The eastbound side of the Don N. Holt Bridge reopened to traffic at about 9:50 a.m. Thursday.
Crews were clearing the bridge at 9:45 a.m. Previously, around 7:10 a.m., the westbound lanes on the bridge were reopened.
The bridge, which connects North Charleston to Daniel Island and Mount Pleasant, was closed Wednesday evening after tarps and other equipment abruptly fell onto vehicles.
Crews worked through the night to remove debris from Interstate 526 and the bridge, authorities said.
Motorists traveling from Mount Pleasant toward West Ashley were detoured from westbound I-526 at Clements Ferry Road before the westbound lanes were reopened. Eastbound I-526 traffic is detoured at Interstate 26.
The tarps and netting were originally in place to catch overspray from a paint job that was being done on the bridge, Law said Thursday.
"It was a safety net," Law said.
The irony of a safety mechanism becoming an obstacle for motorists isn't lost on him, he added.
"The main job it had, it failed at," Law said. "It became the culprit instead of the helper here."
One lane on each side of the bridge will be closed at some point at night so that officials can come to retrieve the fallen tarps and netting, he said.
On Wednesday, traffic came to a standstill around 5:10 p.m. from both directions of the bridge after netting, tarps and cables fell onto the span, according to statements by the North Charleston and Charleston police departments.
About 10 to 12 vehicles were trapped under a fallen tarp, said Spencer Pryor, a North Charleston police spokesman. All occupants were rescued.
While there were no reports of injuries, one person was transported to a hospital after suffering an apparent panic attack, Pryor said. Most of the motorists who were trapped on the bridge were able to contact family members for a ride.
"The Don Holt is expected to be shut down in both directions indefinitely," he said. "(The S.C. Department of Transportation hopes) to have it operational by 5 a.m."
Traffic at a stop onDon Holt EB & WB. Netting/tarp fell down on cars. DOT has been notified and NCPD assiting. Avoid area. pic.twitter.com/VT3zc2GptG— N. Charleston Police (@NCPD) July 19, 2017
Information on what caused the equipment failure was not available on Wednesday.
James Law, a spokesman for the S.C. Department of Transportation, said the incident remains under investigation.
The equipment was set up about three weeks prior to Wednesday so crews could paint the bridge, Law said. The tarps would catch excess paint, the netting was a precaution against equipment falling onto the roadway and the cables were used to secure the tarps and netting.
Department of Transportation engineers will review the situation to determine whether all safety procedures were followed, he said.
Efforts to clear the scene were delayed on Wednesday because the steel cables became entangled with the electrical lighting system at the site, Law said. Crews had to first ensure that there was no risk of electrocution before proceeding to clear the tarps, netting and cables.
Crews with South Carolina Electric and Gas at 6:45 p.m. cut power to lights on the bridge, according to a tweet by the utility company's official account.
The Arthur Ravenel Jr. Bridge also saw heavy traffic following a crash at 4:52 p.m., according to a dispatch supervisor with the Charleston County Consolidated 911 Center.
Both incidents were underway as a powerful thunderstorm moved into the area just before 5 p.m., wreaking havoc on roadways already dealing with rush hour gridlock.
The storm brought lightning, hail and strong winds, according to the National Weather Service's Charleston office. By around 6:45 p.m., the majority of the system had moved on toward the Beaufort area.
The National Weather Service sent out its initial thunderstorm alert at 4:56 p.m. A severe thunderstorm warning followed at 6 p.m. and a flood advisory was in effect until 6:45 p.m.
Conditions included "continuous cloud to ground lightning," gusts of up to 60 mph and nickel-sized hail, the Weather Service said.
Photos from the Don Holt Bridge. pic.twitter.com/o5X6L2z3AP— SCDOT (@SCDOTPress) July 19, 2017