Hostages scream from the hijacked bus at Tanah Merah Ferry Terminal, as the three terrorists menacingly wave their sub-machine guns at them.
But within seconds, the bus is swarmed and surrounded by about 20 men in black from the Singapore Armed Forces' (SAF) Special Operations Task Force and the Singapore Police Force's (SPF) Special Operations Command.
Armed with rifles, hammers and protective armour, the counter-terrorists smash the windows, prop ladders and climb into the bus.
A fierce gunfight ensues and the terrorists are eventually killed or arrested.
The threat is not over.
A bomb in the bus is about to go off.
Personnel from SAF's Chemical, Biological, Radiological and Explosives Defence group are immediately called in.
They diffuse the bomb, but there is no time to rest.
Four other "terrorist attacks" are on - including a ferry hijack, two speedboats trying to approach the Tanah Merah Ferry Terminal, and a bus explosion.
These were the scenarios played out on Wednesday as part of Exercise Highcrest - an inter-agency exercise designed to test the Republic's counter-terrorist capabilities on land and sea.
The exercise, which began on Oct 29, involved more than 1,600 personnel from 20 agencies such as the SAF, Singapore Civil Defence Force, SPF, the Immigration and Checkpoints Authority and Maritime and Port Authority of Singapore (MPA).
Prime Minister Lee Hsien Loong, together with Deputy Prime Minister Teo Chee Hean, Defence Minister Ng Eng Hen and other Cabinet ministers, were also invited to observe the joint exercise on Wednesday.
It was an opportunity to fine-tune inter-agency coordination under the National Maritime Security System, said Rear-Admiral Jackson Chia, the Republic of Singapore Navy's head of naval operations.
"The key takeaway was for the different agencies to work together, from sharing information... to threat analyses. So that as a system we can be even stronger in the years ahead," he said.
Speaking to the media after visiting the exercise, PM Lee said: "We've been doing it for many years and quietly. This exercise is a culmination of several years of work to prepare our national maritime system.
"We have many agencies involved... (and) they have to work seamlessly together. Otherwise, there will be some miscommunication or a clash of plans. Then, we will be in trouble.
"It's not easy to get so many agencies to work together and we have to keep practising and ironing out the kinks. Most important is to put the system in place and that we're working together."
Assistant Superintendent of Police Desmond Ong, commanding officer of the Special Task Squadron, Police Coast Guard, said: "It (the exercise) has enabled us to understand our various roles in keeping Singapore a safe and secured place for everyone."
The 10-day exercise ended on Thursday.
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