Officials say a prisoner was seriously injured while in New Haven police custody.

Police arrested 36-year-old Richard Cox for illegal possession of a handgun Sunday night. 

Acting New Haven Police Chief Regina Rush says Cox was being transported in a police van to the station, when the driver had to make a sudden stop at the corner of Division and Mansfield streets. Cox was injured.

She says the police department has started its own internal investigation.

"The vehicle had to stop abruptly. And Mr. Cox suffered a serious injury, which appears to have impacted his neck and or spine, which may potentially cause his paralysis," said Mayor Justin Elicker.

Officials say Cox was handcuffed at the time of the incident because he was uncooperative while in the police van.

"Regardless of whatever the findings of the investigations are, we are committed to doing everything in our power to make sure an incident of this nature never happens again," said Rush.

The state Attorney General's Office and the Office of the Inspector General are now investigating the incident.