U.S. Senator Bob Casey (D-Pa.) was forced to shelter behind a car for safety during a shooting on Capitol Hill on Thursday afternoon.
"We heard pops and something," he told reporters following the shooting. "All I saw were police officers, and police vehicles."
Casey, along with Senators Rodger Wicker (R- Miss.) and Sherrod Brown (D-OH), were walking back to their offices at nearby Senate office buildings when gunfire erupted around 2:30 p.m. outside the U.S. Capitol.
"We could hear a pop, I don't know whose, it sounded like a firearm, three, four, five pops," he said.
Capitol Police tell NBC News 34-year-old Miriam Carey tried to ram the gates at The White House before leading authorities on a high-speed chase that ended at the U.S. Capitol. Once there, police say, Carey was shot and killed by officers.
One officer was hurt after crashing his cruiser, officials told NBC News. He was medevaced to a nearby hospital for treatment.
Casey said heard what sounded like gunfire immediately before police told them to drop to the ground.
"We said 'Well, why don't we start walking towards the Capitol' and as we did that, that's when they said 'Get down behind the car,'" Casey said.
The senators said they saw police speeding by even before they heard the gunfire.
"There were already police cars going by us before we heard the pops," Brown said. "But there might have been pops before."
Casey, Brown and Wicker hid behind the car for around two minutes when police ushered them inside.
"Then eventually they, I guess they thought that being behind those cars wasn't safe so we took off," Casey said.
The U.S. Capitol and The White House were placed on a lockdown for some time. That has since been lifted.
In a statement following the incident, Casey said he's appreciative of citizen's concerns.
"I appreciate the concern of Pennsylvanians. I am grateful for the fast action and professionalism of the Capitol Police and my thoughts and prayers are with officer who was injured in the incident,” he said.