All the attacks took place in the Whampoa area, over a span of six hours.

The two fair-complexioned men threatened their victims with a combination of broken beer bottle, knife and saw.

The first victim was a 49-year-old woman.

Using a knife and a broken beer bottle, they ambushed her at the void deck of Block 2, St George's Lane, just after 8.30pm. She was forced to hand over her wallet with $10 in cash, her identity card and her $400 mobile phone.

At about 8.40 pm, officers from Rochor Neighbourhood Police Centre were alerted.

But the robbers had already fled. Five minutes later, the police received word that a 34-year-old man had also been threatened by two men - nearby, at Block 1.

Despite having a knife pointed at him, the victim managed to break free and run off.

After interviewing the first two victims, a 12-man team was formed to track the robbers down.

At about 10.30pm, they received word of a third victim - another woman, aged 39.

She had entered a lift at Block 108, McNair Road, at the same time as the duo. One punched her in the face.

They then snatched her $100 cellphone and took $100 in cash before fleeing.

At 2.05am yesterday, a 55-year-old taxi driver picked the pair up along Serangoon Road. They told him to take them to Block 112, McNair Road - near where they had robbed the third victim.

Once there, they pressed a 40-cm saw against the driver's neck and demanded his valuables. He put up a struggle and suffered a cut to his cheek. He finally had to yield to them his $200 cellphone and $160 in cash.

The duo then fled.

By then, police were closing in. The officers spotted a suspect behaving suspiciously at the void deck of Block 34, Bendemeer Road at 3.30am. 'He had an unsteady gait,' said Corporal Lee Hong Ann, 22. The wallet of the first victim was found on him.

The 49-year-old man led officers back to his flat in Block 31, Bendemeer Road. There, they arrested a 38-year-old man found asleep on the living room floor.

Superintendent Lau Peet Meng, the deputy commander of the Central Police Division, said: 'I'm very proud of my offficers for their quick thinking and teamwork.'

The two armed robbert suspects are also being investigated for possible drug offences.

carolynq@sph.com.sg