Almost 100 firefighters and officers are tackling a "sizeable" fire at a library in south east London.
Part of the roof of the Newington Library on Walworth Road, Southwark, is on fire and the crews of 15 engines were expected to spend several hours putting out the blaze, the London Fire Brigade said.
Emergency services were called to the scene shortly after 12.30pm on Monday.
There are currently no indications of how the fire started and no injuries have been reported, a fire brigade spokesman added.
The listed building also houses a museum of Southwark's history and a space for residents to access council services, a spokesperson for Southwark council said.
Leader of the council Peter John said: "Whilst our first concern is for the safety of residents and our staff, we are also worried about possible damage to the museum's collection.
"It does not appear at this time that surrounding buildings or any residential properties have been affected, but we will continue to monitor the situation very closely and continue to assist the emergency services where we can."
Later a fire service spokesman said the whole of the roof of the museum and library was on fire.
Station Manager Peter Critchell, at the scene, said: "Flames are coming through the roof and there is thick grey smoke billowing up. Firefighters are still working hard at the scene to try and bring the blaze under control.
"We now have water jets attacking the fire from the four corners of the building. We evacuated 30 people from inside the museum and firefighters will be making efforts to salvage as many of the artefacts as possible."
Thick plumes of smoke and flames could be seen coming from the building's roof.
Onlookers were kept back by a cordon and took pictures with phone cameras as firefighters battled the flames using aerial platforms.
Peter Critchell, a spokesman for London Fire Brigade at the scene, said 30 people had been evacuated from the property using normal procedures.
"We are fighting the fire from the outside and making a good attack at bringing it under control," he said.
"At the moment the roof has been severely damaged but there will be more inspections needed to see what damage there is inside the building once it is safe for us to get inside.
"There have been a few houses at the rear of the property that we have had to make aware that there is a fire in progress but my understanding is that there has been no large-scale evacuation.
"We will be here for some considerable time yet - we are trying to make sure the fire is well and truly under control and then after that there will be a lot of salvage work, cutting away and damping down and an investigation.
"At the moment the cause of the fire is a matter for investigation and we have no information on how it started."
Richard Rees, a 62-year-old pensioner who works in the community, said: "When I got here the flames were going. The fire services arrived very quickly and did a fantastic job.
"All staff got out very quick and professional, they got out safe. They really didn't know what was going on until they got out and looked up because it was an upper fire.
"It's a listed building, it was one of the very few treasured buildings in the community.
"It took a long time to get it listed and it is a very sad day for us.
"Parts of it are Grade I listed and parts Grade II. It is Victorian and was the old town hall before the big boroughs were set up.
"It is one of three in the borough which the council has been trying to sell off."