PHOENIX - A horrifying ordeal in north Phoenix Monday ended with one man dead and two others in extremely critical condition.

Fire crews from multiple agencies pulled the three unconscious men from a 20-foot-deep hole in a Phoenix underground grain silo.

The Maricopa County Sheriff's Office has identified the man who died as 61-year-old William Tryon. The other men are Christian Silaghi, 33, and Juan Pablo Garcia, whose age is not known.

"They were storing grain and with all the storm flooding were pumping out the water," said Phoenix Fire Captain Reda Bigler.

The incident happened near Carefree Highway and Third Avenue.

The first victim went down in the hole to pump out storm water before succumbing to low oxygen levels.

"When we (fire crews) went down and entered the hole we got readings of four percent," said Captain Reda Bigler.

A typical reading would be around 20 percent.

When the first man did not come back up, a second man went down to rescue him.

The third also went down to check on the others.

"It's unknown how long they were down there but the brain can last only four minutes without oxygen," said Cpt. Bigler.

The two surviving men have been taken to a local hospital in extremely critical condition, according to Phoenix fire officials.

Friends and neighbors of Tryon describe him as a kind-hearted man who worked as a veterinarian.

"There are no words,” said Robin Coleman. “When you think of the greatest person, that was him.”

MCSO investigators were out at the accident scene well into the night trying to figure out exactly what happened.