Good evening. We're following breaking news tonight. A mass shooting in Brian, Texas,

Northwest of Houston, just a few miles from Texas A&M University in college station.

It happened at a local cabinet company. The local police chief says the shooter may have

been employed there. He's now in custody. Chief says at least one person has died, at least

five are wounded, including a state trooper who was shot pursuing the suspect. We've

accrued on the scene gathering information and we'll bring that to you live ahead later

in the hour once we know more. Today in the Derek Chauvin trial testimony from medical

and forensic experts casting yet more doubt on the notion that a drug overdose or some

other existing medical condition killed George Floyd. That in a disturbing account of the

man's final seconds alive. Sinister, a side nurse night reports.

That's the moment the life goes out of his body. I do.

Today, the prosecutor's expert in medical witness did not hold back.

Mr. Floyd died from a low level of oxygen and this caused damage to his brain that we

see and it also caused a PEA arrhythmia that caused his heart to stop.

The world renowned expert on breathing and lungs, Dr. Martin Tobin, pointed to the officer's

actions, saying George Floyd died because the officers created a scenario in which Floyd's

lungs were put into a vice-like grip.

It was almost to the effect as if a surgeon had gone in and removed the lung, not quite,

but along those lines.

Dr. Tobin said four things caused Floyd to stop breathing, including Floyd's position

on the concrete, allowing no room for his lungs to expand.

You mentioned several reasons for Mr. Floyd's low oxygen. You mentioned one handcuffs and

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