SOME flights are resuming after a “credible” bomb threat caused the evacuation of a major Texas airport.

Sniffer dogs confirmed the presence of suspicious substances in the basement of a San Antonio International Airport car park.

A phone threat to police said three bombs had been distributed around the garage, prompting the urgent evacuation about 2:15 p.m. CT (3:15 p.m. ET), a fire department spokeswoman said.

Police sniffer dogs reportedly gave alarms at two of the three vehicles specified in the phone threat. KENS-TV reports pieces of luggage in a parking garage area were being examined.

Two of the three vehicles have since been cleared of containing dangerous substances.

Departing flights had been held, but some arriving planes were allowed to land.

All terminals were swept by security services for possible further explosives. Evacuees were initially held on a hot airport tarmac, but have since been returned to secured areas of the airport terminal.

Some air services have begun to resume.