The man accused of killing 17 people at Marjory Stoneman Douglas High School in Parkland, Florida, in February had a strong physical reaction when a witness came to identify him as the suspected gunman just after his arrest.

According to a police report written by the arresting officer obtained by USA Today, Nikolas Cruz was initially calm when Coconut Creek police officer Michael Leonard spotted the 19-year-old walking in a residential area and approached him.

Leonard reportedly pointed his gun at Cruz, who followed his commands to lie face-down in the grass. When backup arrived, Cruz was handcuffed and stood up to wait for a witness to identify him,

Cruz said during this time that he was having trouble hearing, which the officer presumed was because he had been around gunfire earlier that day.

The suspect’s demeanor reportedly changed when an unknown witness came to identify him as the shooter. According to the report, Cruz “began to move his head and eyes, looking in all directions,” but calmed down when Officer Leonard told him he would be fine.

But when the witness arrived and identified Cruz as the person responsible for the massacre, Cruz  “began to heave and vomited clear fluid,” the officer wrote in the report. He also lost his balance while hyperventilating, and was apparently unable to hold himself up.

The suspect was given a medical evaluation before he was taken to jail.

If convicted, Cruz could face the death penalty. He has reportedly offered to plead guilty to 17 counts of murder and 17 counts of attempted murder if he can avoid being put to death.

[Feature image: Nikolas Cruz/ Taimy Alvarez for South Florida Sun-Sentinel via Associated Press]