Three people were injured on Wednesday morning when an SUV carrying three suspects attempted to ram the gates at the National Security Agency.

The incident happened at around 7.30am at the HQ in Fort Meade, Maryland.

According to FBI agents who are now investigating it, the male driver of the SUV tried to ram it through the gates but was brought to a stop.

There were two other people in the car.

A police officer who was at the scene standing guard shot at its windshield, causing it to plow into the barriers.

They were injured along with a civilian who happened to be at the scene at the time.

All three of the people inside the car are in custody and police have not yet revealed their identities.

The injured includes the car's driver, one police officer and the civilian. None of them were shot but all suffered non life-threatening injuries.

Police have not yet established a motive for the incident but they are confident it was not an act of terrorism.

The suspects' vehicle plowed into the gates outside the NSA on Wednesday after being shot at by guards. The three suspects inside were all arrested

The contents of the SUV's trunk were exposed and there was blood on the ground

'There is no indication to think that this is anything more than an isolated incident," said Gordon Johnson, the Federal Bureau of Investigation's special agent in charge for Baltimore, told a press conference.

'We have no reason to believe that there is any nexus to terrorism.'

The bullet-ridden car remained at the scene for hours after the incident.

The vehicle was at the end of a dead-end lane marked by concrete NSA-stamped barricade blocks on one side and a chain-link fence on the other, near a toll-booth-style entrance gate.

The vehicle had what appeared to be bullet holes in its windshield and extensive front-end damage after crashing into a concrete traffic barrier, according to video of the scene.

'It looks like the gunfire was directed onto the vehicle,' Johnson said, declining to say if weapons were found in the car. No one appeared to have been shot, he said.

After the suspects were arrested, the trunk of the car remained open and revealed several red boxes what looked like large plastic containers.

There were blood stains on the sidewalk immediately behind it.

There were several bullet holes in the SUV's windshield and its windows appeared to be shattered

The male suspect was arrested at the scene. Above, police officers search the car's contents, some of which had spilled out onto the street

The SUV was stopped at one of the gates outside the sprawling HQ. It was not inside or in the parking lot

The roads surrounding the NSA building were closed immediately after the incident but they later reopened

A White House spokeswoman said President Donald Trump had been briefed on the incident.

'Our thoughts and prayers are with everyone that has been affected.

'We will continue to provide updates as they become available,' the White House said in a statement.

The incident bears similarities to a 2015 attempted attack by two men who dressed up as women and drove their sports utility car through the gate.

One of them was killed by police at the scene who shot at the car when they failed to stop.