Sacramento- A veteran Sacramento firefighter has resigned while being investigated in the alleged sexual assault of a woman in a fire vehicle outside the Porn Star Costume Ball earlier this month, authorities said.

The 38-year-old firefighter was one of seven firefighters placed on administrative leave July 3, after they attended the Porn Star event at the Radisson Hotel while on duty.

“Two of the firefighters have been released back to duty though that doesn’t mean disciplinary action is not going to take place,” Sacramento Fire Department spokesman Capt. Niko King said.

The allegations of sexual assault sparked a broader investigation by Sacramento Fire Department officials into firefighter conduct, including picking up women outside bars and drinking while on duty.

The criminal investigation of the alleged sexual assault is in the hands of the Sacramento County District Attorney’s Office, where officials are reviewing an arrest warrant for the former firefighter. The decision whether to charge him is pending, spokeswoman Lana Wyant said Monday.

“It is not taking any longer because he’s a firefighter,” Wyant said. “This case is like any other case that comes into the office.”

She gave no indication of when the District Attorney’s Office would make a decision.

King said the firefighter resigned last week after 10 years as a firefighter and paramedic. The Bee is not using his name because he has not been charged with a crime.

A 24-year-old woman at the Porn Star ball accused him of oral copulation and sexual battery outside the hotel at 500 Leisure Lane.

King would not comment on the firefighter’s personnel record but said the man had received several awards for excellence in service.

The former firefighter declined an interview, saying his resignation was between himself and the department.

Four firefighters remained on administrative leave as fire officials continued their investigation into how long firefighters were at the Radisson, what took place there and who should be held responsible.

The firefighter who resigned was one of four people assigned to the fire engine and the grass fire rig who told emergency dispatchers they were available only by radio from 9:44 p.m. until 11:44 p.m. July 2.

For a shorter period of time, from 9:41 p.m. to 11:15 p.m., two paramedic firefighters assigned to an ambulance also told dispatchers they were available only by radio.

The four firefighters assigned to the ladder truck were at Station 20.

The woman alleged the sexual assault took place at 11:30 p.m. She reported it to police at 1:15 a.m.

Firefighters use the term “available on radio” when they leave the station, whether they are driving to a call, attending a drill or shopping for groceries for the fire station.

The phrase informs dispatchers at the Sacramento Regional Fire/EMS Dispatch Center that the crews are moving within their assigned districts and are available for calls if contacted by radio, dispatch officials said.

“We are responsible for knowing their status, but we do not have any responsibility for knowing where they are at any given time,” said Penny Adams, operations manager for the dispatch center.

Responsibility for knowing what crews are doing and where they are rests with the captain. Station 20, at Arden Way and Del Paso Boulevard in North Sacramento, has two captains: One is in charge of the engine and the grass fire rig, and one is in charge of the ladder truck.

Both captains share responsibility for the ambulance, King said.

Three firefighters from Station 20 who are on paid administrative leave include the captain, the operator who drives the engine and one firefighter.

A fourth firefighter, who was not on duty during the event, is also on paid administrative leave, though officials would not specify the reason.