PARAMUS, N.J. (CBSNewYork) – A sudden explosion rocked an animal hospital in New Jersey Friday.

An MRI machine exploded inside the Oradell Animal Hospital in Paramus, prompting the evacuation of 60 animals.

Three subcontractors were making repairs on the MRI machine at the time.

“I was just driving up as the thing blew up … it’s an old MRI machine which was being dismantled as we speak and a new one installed,” hospital owner Dr. Coleman Palminteri told CBS2’s Christine Sloan.

The explosion caused a ceiling in a small room to collapse but none of the animals were hurt because they were in a different part of the building, Sloan reported.

Three outside contractors repairing the machine were hurt. One man is in critical condition, 1010 WINS’ Carol D’Auria reported.

“No animals or any of our staff were injured,” Palminteri said.

Four of the animals that had been in critical condition were rushed to other hospitals.

Other animals were evacuated to a nearby building and their owners rushed to the hospital.

“I am happy she’s all right,” said pet owner Joe Morocco of Weehawken.

People and pets evacuated following an incident at Oradell Animal Hospital on March 6, 2015. (credit: Debby Hastings via Twitter)

People and pets evacuated following an incident at Oradell Animal Hospital on March 6, 2015. (credit: Debby Hastings via Twitter)

Deborah Hastings was in an examination room with her two dogs.

“Everybody was kind of scared, you know? People were very nervous, and kind of, you know, quite upset. I don’t know if they had to leave their dogs in there or not,” Hastings told 1010 WINS. “Certainly dogs on stretchers and oxygen tanks and stuff.”

Numerous people were standing with pets in the parking lot outside the hospital.

“We all went out, everybody was starting to gather out front. There were dogs on stretchers, not a lot of them, but some,” Hastings said. “Everybody had an attendant.”

“There was helium released after the explosion but we cannot confirm what set the explosion off at this time,” said Paramus Police Chief Kenneth Ehrenberg.

Although officials said the building is structurally sound, they don’t know when everyone will be allowed back in, Sloan reported.

OSHA is investigating.