An interstate highway in South Carolina has been shut down as authorities respond to a bomb threat involving an 18-wheeler, the governor’s office has confirmed.

The ongoing incident unfolded at around 3:30 p.m. on Thursday afternoon near Greenville.

State and local authorities swarmed I-85 near mile marker 44 and blocked traffic in both directions.

“I-85 NB and SB in Greenville is closed near MM 44 due to an incident. Both sides of the I-85 are closed until further notice. Detours are posted, but the public is urged to avoid I-85 in this area until further notice,” South Carolina Highway Patrol Trooper Mitchell Ridgeway announced on social media just before 5 p.m. local time.

Aerial footage circulating on social media shows a number of law enforcement vehicles parked a substantial distance from a tractor-trailer sitting in the roadway near an off-ramp.

“I-85 near mile marker 44 is temporarily closed out of an abundance of caution due to a bomb threat issued during a routine traffic stop this afternoon by SC Transport Police,” Gov. Henry McMaster’s office explained in a statement posted to social media.