She heard a scream while at work in her printing company on Tuesday morning.
Ms Lee's (not her full name) male colleague's hand was stuck in a large industrial-grade printing machine.
The sight made her fear the worst.
But miraculously, even though the 64-year-old man's hand was trapped by the printer's rollers, it did not have to be amputated. The accident happened on Tuesday around 11.30am at printing company Citi Print & Design at Ubi Techpark.
The man had been adding lubricant to the machine while it was running when his right hand and forearm got trapped between the rollers of the machine.
Ms Lee, who has been working at the company for five years, called another colleague for help when she heard the scream. She said: "I've never seen anything like this in all my years of working here."
Her colleagues switched off the machine and tried to free the man.
The Singapore Civil Defence Force (SCDF) said they were alerted to the incident at 11.30am and sent a fire engine, a Red Rhino, two fire bikes, one ambulance and two support vehicles to the scene.
Major Lok Wee Keong, commander of the Paya Lebar Fire Station, led the rescue.
He told The New Paper they found the victim standing with his right arm trapped. He said the man looked calm.
"By the time I arrived, the paramedics had given him an oxygen mask and told me that his vital signs were stable," he said.
Maj Lok said technicians there used tools like a spanner and screwdriver to help the man before the SCDF arrived.
"My team and I dismantled the side cover of the machine, exposing the chains.
"We also cut a series of beams, bars and supporting rollers to free his hand," he said.
He said he could see about eight to 10 rollers of different sizes amid grease and dirt.
The rescue was completed within 20 minutes.