NEW YORK—A fire set by an inmate at New York City’s troubled Rikers Island injured 20 people on a day that lawmakers visited the jail complex, authorities said.

Fifteen staff members and five inmates were injured in the fire that started at about 1:30 p.m. Thursday, the city Correction Department said. The New York City Fire Department extinguished the blaze within an hour, a department spokesperson said.

Fifteen of the injured were taken to hospitals for treatment, while the other five declined medical attention, the Fire Department said. Information on the victims’ conditions was not available Friday.

“The health and safety of those who work and live in our facilities is our main priority,” James Boyd, the Correction Department’s deputy commissioner for public information, said in a statement. “We take arson very seriously, and will pursue re-arrest of the individual involved pending the outcome of the investigation.”

The fire broke out on a day when a group of Democratic state lawmakers visited Rikers Island to underscore their opposition to Gov. Kathy Hochul’s proposed changes to New York’s bail laws. The plan to give judges greater leeway in setting bail is among the key issues stalling negotiations over the state budget.

The state legislators did not visit the unit where the fire took place and appear to have left before it was reported.