Fire investigators today were trying to determine the cause of a three-alarm fire that extensively damaged a pharmacy and caused smoke and water damage to the Fells Point studio of a renowned artist.

The fire broke out in the front of the REVCO pharmacy at South Broadway and Eastern Avenue about 12:14 p.m. yesterday and quickly raced through much of the store. The fire also reached the upstairs art studio that is owned by Grace Hartigan, an abstract impressionist whose works are featured in many galleries here and in other cities.

Hartigan is working on a series of paintings ranging in price from $15,000 to $50,000 that are set to be exhibited April 2 at Constantine Grimaldis' gallery at 1006 Morton St.

It was not immediately known if any of the works were damaged by the fire.

Fire officials said it took firefighters from several stations about an hour to gain control of the fire that forced Hartigan and two employees to flee. No injuries were reported.

At the time of the fire, the pharmacy was closed.

Hartigan reported she was in her studio and putting the finishing touches on a painting titled "The French Doll" when she saw smoke coming up from the store below.

Hartigan said she left by a door on the Eastern Avenue side of the building and that her assistants, a man and a woman, escaped by ladders provided by firefighters on the Broadway side.

A fire official said most of the art studio escaped the flames, but he said that it did receive some smoke and water damage.