OAKLAND -- The promoters of a Saturday night Halloween party in downtown Oakland where nine people were shot did not have the proper permit to hold the event, officials said Monday.

That could result in Sweet's Ballroom, the historic venue at 1933 Broadway where the Fright Fest was held, possibly losing its cabaret license and forcing future events elsewhere, officials said.

Officer Jeff Thomason, a police spokesman, said city officials had notified all cabaret license holders that if any Halloween parties were to be held at their facilities a special event permit issued by Oakland police was required.

Thomason said none was obtained for the party.

Arturo Sanchez, a city official who oversees the department that issues the permits, said a special event permit issued by police is required anytime a venue such as Sweet's uses an outside promoter or holds a special event such as Saturday's party that is likely to draw a larger than usual crowd.

At least 600 attendees were at the party.

Police could have denied the permit request but most likely would have mandated additional requirements, such as more private security and paid uniformed Oakland police officers, before issuing one.

Sanchez said the city will pursue a nuisance action and all available enforcement options, including suspension/revocation of the cabaret permit for failure to abide by cabaret conditions and requirements of the Oakland Municipal Code.

That could jeopardize the popular Ecstatic Dance events as well as a host of others held in the 76-year-old ballroom, official said.

Representatives of Sweet's and the party promoter, an organization known only as THA Officials, could not be reached for comment about the lack of the permit.

Police on Monday continued to investigate the shooting, which is thought to be the largest number of victims shot in Oakland at one time at least since the late 1980s.

Investigators are trying to identify the gunman and establish a motive.

The nine people wounded ranged in age from 18 to 28 and were from Richmond, Antioch and San Francisco, authorities said. Five of the victims are women, officials said.

It is still that an 18-year-old man wounded in the stomach was the main target and the other people innocent victims hit by errant bullets.

An 18-year-old woman was hit in the back, another 18-year-old man was wounded in the buttocks and the rest of the victims were hit in their arms and or legs.

The shooting happened at 12:01 a.m. inside the facility where 600 people had been dancing and listening to music since 9:30 p.m. The event, billed by promoters as "the biggest college party in the Bay Area," had been promoted on various websites and cost $15 for admission.

A Sweet's employee said earlier that 16 security guards were present and that people had been frisked before being allowed to enter.

It was advertised that Oakland police would be present, but city officials said no officers had been requested.

Sweet's cabaret permit was issued to Friends of Creation Spirituality, Inc., with former theologian Matthew Fox as the president, officials said.

They sold the building in 2002 in return for a lease that would expire in 2037.

Sweet's came close to losing its cabaret license in July 2009 after two separate scuffles broke out near the entrance.

The cabaret permit is still valid, Sanchez said, although Fox and his organization ceased to operate the two-story building several months ago. The landlord of the building is Mahmoud Mohammed Elmiari, of Foster City, according to city records.

Police and Crime Stoppers of Oakland are offering as much as $45,000 in reward money for information leading to the arrest of the gunman.

Anyone with information can call police at 510-238-3426 or Crime Stoppers at 510-777-8572 or 510-777-3211.