SINGAPORE - Scenarios of terror attacks were played out at several locations across Singapore on Wednesday (Nov 18) morning, as part of an annual anti-terror exercise codenamed Exercise Heartbeat.

Led by the Singapore Police Force (SPF) along with other departments of the Home Team, one of the scenarios - simulating a chemical agent attack - was conducted at One Marina Boulevard in the heart of the Central Business District around 9.30am.

In the exercise, a group of office workers were 'foaming at the mouth' and 'suffering from fits', as Singapore Civil Defence Force (SCDF) frontline firefighters from Marina Bay fire station and hazmat specialists arrived at the scene.

Sarin gas, a colourless and odourless nerve agent, was used in the attack.

The second scenario was held at Esplanade Park and involved two different types of attacks - an improvised explosive device (IED) explosion and a gunman shooting.

Office workers were initially evacuated from the HSBC Building to the nearby Esplanade Park due to the discovery of a suspicious vehicle inside the building.

But the lone terrorist, armed with a gun, had anticipated the evacuation and planted a bomb at the park instead. A hostage situation developed before SPF and SCDF personnel stepped in.

Senior Minister of State for Home Affairs Desmond Lee was present to witness the exercise, which is into its seventh year.

In light of the recent terrorist attacks that happened in Paris and other parts of the world, Mr Lee said it was critical that Singapore remain vigilant at all times.

"Exercises such as Exercise Heartbeat test the readiness of the Home Team and the community to respond in the event of such incidents," he added.

Earlier Wednesday morning, another scenario featuring a simulated terrorist swarm attack took place at the HDB Hub in Toa Payoh between 1am and 4.30am.

A final scenario will be held on Nov 23 at the Sentosa Golf Club and Sentosa Cove Village. It will involve a suicide bomber and gunman attack.