Prince George's County firefighters yesterday took over round-the-clock operations at the Riverdale Fire Department after volunteers at the station refused to respond to ambulance calls.

The town of Riverdale Park yesterday obtained a restraining order banning the volunteers from working at the department for the next 10 days, citing "an immediate threat to the public health, safety and welfare."

The volunteers, who had staffed the department at night and on weekends, recently told Prince George's Fire Chief Ronald J. Siarnicki that they would continue taking fire calls but stop answering ambulance calls because they did not have enough staff.

Siarnicki ordered the department to answer the ambulance calls, and he demoted several volunteer leaders who refused to comply. Firefighters in neighboring communities have been answering ambulance calls the volunteers refused to handle.

Last night, paid firefighters were staffing the station, said Timothy F. Maloney, an attorney for Riverdale Park. The paid firefighters were using reserve county equipment. The volunteers had hidden the ambulance that they used and own.

About 5 p.m. yesterday, a lone volunteer answered the phone at the station. His presence was an apparent violation of the court order, which was signed yesterday afternoon by Prince George's Circuit Court Judge Maureen Lamasney.

Asked about the restraining order, the volunteer, who would not give his name, said, "That's the first I've heard of it. I don't know anything about it now." The volunteer declined further comment and left the station. Riverdale volunteer leaders could not be reached for comment.

In court papers filed yesterday, Riverdale Park, which owns the fire station, argued that the volunteers needed to be evicted from the station to allow paid firefighters to take over.

In a letter to town officials, Siarnicki offered to staff the station for the next 30 days, providing a "cooling off period to attempt to address the serious management issues that exist."

County fire officials said relations with the volunteers have been strained since last month when volunteers tried to block the county from moving one of the station's fire engines to another department. County officials said they took ownership of the truck after volunteers said they could no longer make payments on it.