PHOENIX (3TV/CBS 5)-- Three people are dead and three firefighters are hurt following a crash in Phoenix Sunday morning.

The crash involving a Phoenix fire truck and a pickup truck occurred at around 9:15 a.m. at 29th Avenue and Bethany Home Road.

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According to Sgt. Vince Lewis, the fire truck was heading to a structure fire nearby when the collision happened. Lewis added the fire truck had its lights and sirens on.

[PHOTOS: Fire truck involved in deadly crash in Phoenix]

Two adults and a 4-month-old baby were inside the truck at the time of the crash.

Phoenix police said 20-year-old Kenneth Collins was pronounced dead at the scene.

The 4-month-old child, Kenneth Collins Jr., and 19-year-old Dariana Serrano were taken to the hospital where they died from their injuries.

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All three firefighters were transported to Banner University Medical Center and treated for their injuries.

One of the firefighters has been released from the hospital.

The other two firefighters remain at the hospital for observation.

Witnesses who saw the accident say it sounded like a bomb exploding.

"You could hear a big boom. You could hear that truck go boom, boom, boom three times; it flipped three times," said Pete Benitez, who says the crash happened right in front of him as he was driving.

“I heard the siren coming down the street and I heard the engine and then all of a sudden I heard the explosion,” said Deacon Bryan Root, who was opening the doors to the church that was right near the accident site. He heard the horrific crash and then tried to help.

[VIDEO: Fire truck, pickup collide in deadly crash that killed 3]

“The siren stopped immediately and I heard multiple booms and I knew something bad had happened,” said Root.

That boom was the pickup truck and fire truck colliding.

"We just saw them flipping! We saw this one flip and this one flip," said Benitez.

Although police are still investigating, it appears the pick-up truck turned left in front of the fire truck. The force of the crash caused the fire truck to roll several times and come to a rest in a school yard.

"The blue pickup truck he turned right in front of them,” said Benitez.

“I ran as fast as I could over there and saw a fire truck laying in the middle of the field. And they had kicked out the windshield and were crawling through the windshield,” said Root.

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Root tried to help when he saw the firefighters seriously and he says even in their state of injury and in and out of consciousness, their instinct to help was still intact.

“When they pulled them out it looked like they had at least concussions, but very severe lacerations all over their head and they were discombobulated. The firemen immediately were getting emotional because they seemed to know what had happened to the people in the truck right away. They wanted to go help but they were told just to lie there,” said Root.

The names of the victims and firefighters have not been released at this time.

Bethany Home Road was closed for hours from 27th to 31st avenues, finally reopening around 9:30 p.m.

[PHOTOS: Fire truck involved in deadly crash in Phoenix]

The exact cause of the crash remains under investigation.

It is policy, that a firetruck may go 10 miles over the posted speed limit while responding to a call with lights and sirens.