Shouts and gunshots punctuated the air as three "gunmen" in masks stormed the lobby of a Sentosa attraction and opened fire on more than 10 people.

A few minutes later, a group of officers from the Singapore Police Force's (SPF) Ground Response Force and Emergency Response Team arrived at the scene and, after a brief shootout, shot and handcuffed the "gunmen".

The simulated terror attack yesterday at one of Sentosa's attractions, KidZania Singapore, was part of this year's Exercise Heartbeat, which aims to boost incident preparedness and response during peacetime.

The hour-long simulation involved more than 200 role players and officers from the SPF and Singapore Civil Defence Force (SCDF).

The annual exercise, which is in its 10th year, was jointly organised by the SPF, Sentosa Development Corporation (SDC) and the Ministry of Manpower (MOM), and supported by KidZania Singapore and the SCDF.

The exercise also saw SCDF tending to the "casualties" outside the building by bandaging their wounds, attaching drips, providing oxygen masks and monitoring their pulses.

Prior to the exercise, as part of the SGSecure at Workplaces programme, KidZania had partnered SDC, SPF and MOM to review its crisis response and business continuity plans.

The programme engages companies on the need to prepare themselves against terror threats in the workplace.

KidZania Singapore general manager Leong Yue Weng said: "While we have detailed contingency plans in place, this joint exercise allows us to put our emergency preparedness measures to the test and work with various agencies to fine-tune them."

Sentosa is home to more than 6,000 residents and receives 19 million visitors annually.

SDC, which oversees the development, management and promotion of the island, organises about 50 exercises and drills every year, with scenarios ranging from business disruptions to those related to safety and security. It also conducts training and workshops to equip tenants, staff and residents with risk management skills against terror threats.

SDC chief executive Quek Swee Kuan said: "It is of utmost importance that we stand ready to respond effectively to any emergencies so that everyone in Sentosa has peace of mind."

Mr Patrick Tay, an MP for West Coast GRC, who observed the exercise, said it is important for Home Team agencies, business stakeholders and the public to work together to tackle potential threats. "Today's exercise is a great platform for them to come together... to raise awareness and work out some of these coordination efforts," he said.

Companies can find out more about SGSecure at www.sgsecure.sg and www.mom.gov.sg/sgsecure