DALLAS (CBS11) – Two weeks from now, the City of Dallas will remember those killed an injured during the July 7, 2016 police ambush in downtown.

Much of the drama from that night happened a few miles to the north at Parkland Hospital where nurses and surgeons are sharing their story for the first time to CBS11.

Parkland Hospital activated its code three disaster mode on July 7 and locked down the emergency room during the most challenging night in its history.

Pager alerts were the first sign something bad was happening and that the staff of Parkland’s emergency room needed to get ready.

“We all carry these pagers still and the trauma disaster page went off,” says Doctor Brian Williams who was working when the first wounded officers from the ambush started coming in.

“I don’t even look at the entire trauma center the same,” says Williams.

“We don’t typically see a lot of injuries like that they were pretty massive injuries,” says Jorie Klein, Parkland Director of Trauma Services.

She desperately tried to save three dying officers and wondered how many would keep coming.

“The greatest concern was we didn’t know what was going on we knew there was a march downtown but we had no idea what the shooting was about who was shooting why they were shooting,” says Klein.

Doctor Alex Eastman was downtown. He’s a Dallas Police SWAT officer and a Parkland trauma surgeon.

“So on the way in via the radio I’m trying to direct us not to take all of the casualties to one place,” says Eastman.

Still, most of the injured and dying officer’s came here to Parkland, each surrounded by teams of 12 working into the night in the hospital’s new state-of-the-art trauma rooms.

“To me, this is one of the most catastrophic events I worked the Branch Davidians several plane crashes,” says Klein.

Work in any emergency room is never normal. Saving lives is a job requirement.

But what happened nearly one year ago had an impact on even these battle-scarred medics.

“People had a hard time dealing with it,” says Eastman.

“It’s been transformative for me I’m definitely not the same person I was before this event happen,” says Williams.

Parkland’s staff says it learned a lot from the incident and made some changes including moving some of their blood supply closer the trauma rooms.