Drivers waited in gridlock traffic and students at West Ashley High School were dismissed late while Charleston police investigated a bomb threat at a Goodwill store Wednesday.

No bomb was found during a search, and no one was injured during the incident, police said.

A section of Glenn McConnell Parkway from Wildcat Boulevard to Bees Ferry Road was shut down for about four hours while police investigated the threat. Shelby Ray Court between Mary Ader Drive and Goodwill Court also were closed during the incident.

The roads reopened around 4 p.m.

A man called in the bomb threat to Goodwill, at 3516 Shelby Ray Court, at 11:08 a.m. The building was evacuated while police investigated, police spokesman Charles Francis said.

West Ashley High's dismissal was delayed because of a lockdown sparked by the possible threat at the store, which is less than a mile away. Dismissal started about 30 minutes after the scheduled dismissal time of 2:15 p.m.

First, school buses were allowed on the campus, district officials said. Then, Charleston police allowed parents access to the school on Glenn McConnell Parkway from the Magwood Drive end, school district officials said.

The school dismissed the rest of the students in stages, because of nearby police activity and traffic congestion.

Police are continuing to investigate the origin of the threat. No arrests had been made by late Wednesday.