SAN MARINO — A massive fire caused an estimated $2 million worth of damage to a real estate office early Friday, authorities said.

No one was injured in the four-alarm blaze, which was first reported at 1:11 a.m. at Masters Realty, 2476 Huntington Drive, San Marino Fire Department officials said in a written statement.

The cause of the fire remained under investigation Friday, San Marino Fire Department Division Chief Rick Mayhew said.

“They’re actually still trying to dig through all of the rubble to get to the actual point of origin,” Mayhew said.

Firefighters arrived to find heavy smoke pouring out of the windows of the business, officials said. They immediately called for additional firefighters and began attacking the flames.

“The extreme fire conditions inside the occupancy kept firefighters from advancing any further into the structure,” the statement said.

Firefighters then called for additional backup and used large, truck-mounted hoses to control the fire before sending personnel in with handheld hoses, officials said.

Authorities continued battling the blaze for more than two and a half hours, fire officials said.

“Due to the effective actions all firefighters on scene, the fire was contained to the occupancy of origin, thus preventing any losses to the adjacent business,” according to the written statement.

The neighboring business attached to Masters Realty sustained only minor damage, Mayhew said.

In addition to the San Marino Fire Department, officials from the Los Angeles County, San Gabriel, Alhambra, Arcadia, Pasadena, South Pasadena, Monterey Park and Glendale assisted with the fire.

The fire departments make up a cooperative team of agencies that often works and trains with each other, Mayhew explained.

“They did an outstanding job, Mayhew said. “They work really well together.”