The main entrance to North Island Naval Air Station near San Diego was closed for hours Tuesday after a motorist was found with bomb-making materials, a military spokesperson said.

The vehicle approached the gate at about 9 a.m. and was stopped and searched at the request of Naval Criminal Investigative Service officials, Naval Base Coronado spokesperson Kevin Dixon told the San Diego Union-Tribune.

The search turned up bomb-making materials that were not assembled into any kind of device, Dixon said. Officials detained the driver in for questioning, the Union-Tribune said.

While the main entrance was closed, entry to the base was still available through two other gates.

Shortly after 2 p.m., base officials posted a notice on Facebook that the main gates had reopened, shelter-in-place orders had been lifted and normal operations had resumed.

Naval Air Station North Island is one of eight U.S. military installations that make up Naval Base Coronado.