It was over in a flash.

After tossing in stun grenades, a dozen officers from the Special Operations Task Force (SOTF) burst into the pitch-dark cinema hall, guns blazing.

By the time the lights came on seconds later, four of the five "terrorists" who had taken about 40 people hostage in a Golden Village cinema at Tampines Mall, were dead. The one remaining "terrorist" rose to take a potshot at an officer as the team checked the aisles, but he too was quickly dispatched.

The adrenaline-pumping action was part of a media preview of the islandwide counter-terrorism exercise that started yesterday and ended in the wee hours this morning.

The preview, held hours before the operation began at 10am, involved SOTF officers from the Singapore Armed Forces (SAF) storming the cinema hall after terrorists launched a coordinated strike on malls in Bishan and Tampines.

Armed terrorists attacked the Century Square shopping mall first, before hitting the adjacent Tampines Mall, barging into cinema hall 1 as a movie played, firing blanks at the ceiling, and yelling: "Get down and shut up!"

They commanded hostages to take pictures and post them on social media. To let the hostages know they were not joking, they picked a man at random and shot him in front of the crowd.

"All of you better cooperate with us, or I will make sure you suffer and die," said one of the terrorists.

Later, one of the hostages was strapped with a suicide vest as he cried for help.

Said one of the terrorists: "We are ready to die, are you?"

Moments later, the SOTF officers broke in. Armed with night-vision goggles, they fired blanks from their HK-416 assault rifles and P-90 sub-machine guns in the darkness, quickly neutralising the terrorists.

"Everyone listen up, we are from the Singapore Armed Forces, we are here to rescue you," said one of the officers to the hostages.

Outside the cinema, police officers formed a security cordon - the exercise was meant to test coordination between different agencies.

The moviegoers, played by SAF servicemen, were swiftly marched out with their hands on their heads, while the hostage who had explosives strapped onto him had the suicide vest removed.

It was later "detonated" in a controlled explosion inside the cinema hall, after the SOTF officers and hostages had left.

In later parts of the operation, officers from the Singapore Civil Defence Force tended to the injured, while the Immigration and Checkpoints Authority would go on to nab a "terrorist" attempting to flee the country.