By Shariq Khan, Nicole Jao and Stephanie Kelly

NEW YORK (Reuters) -A fire ignited at BP's 440,000 barrel-per-day oil refinery in Whiting, Indiana, before it was extinguished on Friday morning, the company said.

The blaze at the largest refinery in the U.S. Midwest caused gasoline prices to spike in parts of the region.

The fire resulted from an operational incident, and there were no injuries, the company said in an emailed statement. It did not elaborate on the incident.

Reuters earlier reported multiple units were offline, according to two market sources that were citing data from consultancy Wood Mackenzie.

REFINERY WAS FLARING

The refinery was actively flaring, the controlled burning of excess gas, early on Friday, one of the sources said, citing a Wood Mackenzie camera feed of the plant.

Wood Mackenzie confirmed it had issued an alert to clients saying the 255,000-bpd crude distillation unit, associated 60,325-bpd vacuum distillation unit, 100,000-bpd cat feed hydrotreater, and 24,300-bpd hydrotreater were shut during the early morning.

In addition, the 115,000-bpd fluid catalytic cracker was shut on Thursday evening, Wood Mackenzie said in the alert.

The crude distillation unit could be down for at least a week, two sources said.

BP said the community may have heard internal refinery sirens and noticed flaring, but the company did not immediately respond to questions about the plant's operational status.

The refinery in mid-September began planned maintenance work on its units, including the 90,000-bpd crude processing unit and a 65,000-bpd fluid catalytic cracker, according to industry monitor IIR. The planned turnaround was expected to last for two months.

In August, the refinery took multiple units offline for more than a week due to flooding caused by a severe thunderstorm overnight.

The refinery produces a wide range of liquid fuels, including gasoline, diesel, and jet fuel.

"Great Lakes spot gasoline prices spiking on the BP refinery fire overnight, could lead to prices cycling soon. For now, wholesale prices pointing to about a 20c/gal rise," Patrick De Haan, head of petroleum analysis for GasBuddy, said in a post on X.

Gasoline prices in Midwest spot markets had also jumped earlier this week due to tightening supplies, as multiple regional refineries have taken units offline for maintenance, traders said. [PRO/U]

(Reporting by Nicole Jao and Shariq Khan in New York, Stephanie Kelly in London, Anushree Mukherjee in Bengaluru; editing by Barbara Lewis and Rod Nickel)