A rental car parked at the Phoenix terminal has triggered a massive security alert that has interrupted the airport for hours

Terminal 4 at Phoenix Sky Harbor Airport reopened following a huge safety alert after a suspicious and unoccupied vehicle was found in a curb lane.

The rental vehicle was later deemed safe after it was discovered on the upper deck of Terminal 4 around 7 am on 16 September.

The entire terminal was closed as a precautionary measure as authorities investigated the vehicle, causing the cancellation of dozens of flights and thousands of passengers stranded at the airport for more than four hours.

An airport spokesman said that three of the four security checkpoints at the terminal had also been closed as a precaution, the airport's Sky Train not dropping passengers at Terminal 4 during the weekend. # 39; investigation.

Phoenix police sergeant Tommy Thompson also warned that people could hear "loud explosions" as the bomb team examined the silver Nissan, reports ABC 15.

Although frustrated, the passengers described how the situation could have been much worse.

"The people are surprisingly calm," said Dian Squire, one of those who had to wait at the airport for several hours at AZ Central. "I think a security threat is more manageable in people's minds than a delay on the plane for other reasons, and I bet it's different for people stuck in the terminal itself. "

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A Southwest aircraft is seen on the tarmac at Phoenix Sky Harbor International Airport on September 19, 2016 in Phoenix, Arizona. Terminal 4 was closed for several hours as a precaution following the discovery of a suspect parked vehicle. DANIEL SLIM / AFP / Getty Images

After the car was finally judged safe, Alliance towing owner Richard Polanco Jr asked him to tow cars left at the airport for almost a decade.

Polanco told AZ Central that he had spoken to the driver of the car, who told him that he would only leave his car for a few minutes while he was running inside the car. Airport to help her friend to check in.

"He was just disappointed that something so small – a silly mistake he made – had become so serious," Polanco told AZ Central.

Chris Gaastra, one of those who had to postpone flights after the disruption, also described his frustration.

"I can not do anything about it and I'm glad it's not a bomb," she said. "Sad person was so stupid."

The airport then wrote on Twitter: "Operations are returning to normal at Terminal 4. Travelers are encouraged to continue to check their flight status with their airlines."

The man who left the rental, whose name will not be made public by the police while he has not been arrested, will be given a parking quote and will be fined approximately $ 56.