It was a typical afternoon at Northpoint Shopping Centre until what seemed like a scene from a horror story shocked shoppers and workers there.

A young man, his clothes drenched in blood, was seen stumbling out of a toilet. He collapsed in front of a foodcourt, alarming the people around him.

What followed were shouts and calls for help. Several people ran to his side, talking to the man in the hope of getting a response.

"He did not speak, but the up and down movement of his abdomen told me he was still alive," said Madam May Wong, 51, an employee of Chen Kang Wellness, a massage parlour near where the man collapsed yesterday afternoon.

She had been on her phone when she heard a thump. When she turned towards the sound, she saw a man lying motionless on the ground, and ran towards him with several other colleagues.

Blood had soaked through his green T-shirt, and his arms were also bloodied, she said in Mandarin.

"He looked like an NSF boy. Very young. My heart hurts just thinking about it," she said.

The man has not been identified, but the police told The Straits Times he is 20 years old. He sported the crew cut common to full-time national servicemen (NSFs).

Employees of nearby shops said they did not see anyone running from the scene.

The man had collapsed in front of the Cantine foodcourt on the Yishun mall's third floor around 1pm.

Kopitiam, which operates Cantine, said the incident did not happen in the foodcourt.

A spokesman said the man had come out of the toilet before collapsing in front of the foodcourt.

The Singapore Civil Defence Force (SCDF) said it received a call for assistance at the mall at 1.22pm, and dispatched an ambulance.

The man was found in a semi-conscious state and taken to Khoo Teck Puat Hospital.

The Straits Times understands that he had multiple injuries.

According to another employee of Chen Kang Wellness, there were no visible stab wounds on the man's abdomen when SCDF officers lifted his T-shirt.

The 38-year-old witness, who declined to be named, said most of the blood had collected near the man's neck."It seemed like there was a gash there," he said.

A spokesman for Frasers Centrepoint Malls, which manages Northpoint Shopping Centre, said the police cordoned off the area for about an hour, during which patrons were redirected around it.

"We continue to work closely with the police to support their investigations," she said.

Pictures of the youth's bloodied body went viral on social media, prompting speculation that a murder or stabbing had occurred.

But police said preliminary investigations suggest that it may have been a case of attempted suicide.