PHOTOS: Firefighters battle extra-alarm blaze at former school building in Lincoln Park

CHICAGO (WLS) -- Chicago firefighters are working to extinguish a three-alarm blaze at the former James Mulligan Public School Building in the city's Lincoln Park neighborhood.

Dozens of firefighters responded to the scene in the 1800-block of North Sheffield Avenue around 2 a.m. Tuesday, where flames could be seen shooting out of the top two floors. Neighbors were evacuated from their homes as a precaution.

The 124-year-old structure was empty and appeared to be under construction when the fire broke out. There is no word on injuries or what may have sparked the fire.

CTA Purple Line service was suspended from Howard to the Loop. Brown Line trains were also re-routed Tuesday morning. Red Line service was temporarily suspended between the Belmont and Grand stations but was back in service by about 2:10 a.m., operating with residual delays, according to the CTA.

The building, which first opened for students in September 1890, was being considered for historic landmark status in February, according to a city document. It was closed in the early 2000s and remained vacant until the Board of Education sold it to a private developer, the document said.

The Sun-Times Media Wire contributed to this report.