No injuries were reported after a United Airlines Boeing 757 jet backed into a Sky West plane which was carrying 60 passengers on Sunday night at the San Francisco International Airport.

According to San Francisco Chronicle, the accident occurred around 7:30 p.m. when the United plane was pushed by a “tug” to a hangar from Gate 80. No passengers were on board.

United plane hit the Sky West plane which was preparing to head to Boise, Idaho and had on board 60 passengers who were not injured, according to Airport Duty Manager Lily Wang.

The passengers were immediately removed from the plane by a stairway.

Both of the planes suffered damages to their tails and engines.

Wang said: "The 757's tail basically went on top of the regional jet. It is human error. It is dark out there, it is nighttime. It could be (United) not seeing that other airplane because it is very low."

The Federal Aviation Administration will investigate the cause of the crash.

The United plane had aboard maintenance workers as it was pushed to the hangar, including two in the cockpit who steered it, but no “wing walkers” were on the ground to direct the “tug.”  

United Airlines spokeswoman Robin Urbanski said: "Because the plane was being pushed to the maintenance, wing walkers were not used. Whenever something like this happens, of course we are concerned and we will have to investigate further." She said that is the procedure when a plane is taken to the maintenance.

The passengers who were taken from the Sky West plane were accommodated at local hotels and will be on the first available flight to Boise in the morning.

Airport Duty Manager John Ginty said that the airport's main taxiway - the eastbound - was closed from the time of the accident until 8:48 p.m. No delays were recorded as the planes were sent to the other taxiway.

A report issued by the FAA in October last year showed that the San Francisco International Airport is one of the riskiest airports in the country when it comes to collision of planes.