About a hundred staff fled Tang Plaza yesterday after a fire broke out at around 9am.
No one was injured in the blaze, which started on the third-storey roof above the building's side entrance, facing Lucky Plaza.
The Orchard Road building houses the Singapore Marriott Hotel and Tangs department store.
The Singapore Civil Defence Force (SCDF) said the fire was spotted by a member of the security staff who immediately alerted the building's Fire Command Centre. The centre deployed its in-house firefighting team for initial firefighting operations.
The SCDF, which was called at 9.10am, arrived with two fire engines, two red rhinos, two fire bikes, an ambulance and three support vehicles. The blaze was extinguished by the SCDF using a water jet and two hose reels within 20 minutes. The cause of the fire is still under investigation.
When The Straits Times arrived at the scene around 10am, SCDF officers were still examining the site. Water was streaming down from the roof, where burn marks could be spotted.
An area between Tang Plaza and Lucky Plaza was cordoned off by police, but that did not stop hundreds of passers-by from gathering to check out the commotion.
Mr Mahendran Ramalingam, 32, the store manager of Tiong Bahru Bakery at Tang Plaza, said there was an announcement alerting them to the fire at about 9am.
Mr Mahendran, who described the fire as "small", said he saw only black smoke, but "not a lot".
Tang Plaza's chief security officer Luke Tan did not give further details but said: "We hold fire drills often. All procedures were adhered to and everyone was taken care of."