A man waving what looked like a samurai sword struck fear in train passengers around lunchtime on Monday.
He boarded a train at Paya Lebar MRT station and was later arrested at Bugis, the police said in a statement Monday evening.
This is what witnesses saw:
ON THE TRAIN
What started off as a normal trip on the MRT on Monday afternoon turned into a white-knuckle experience because of a man wielding a samurai sword.
Mr Ow Yong Weng Leong, 33, said he had boarded the train at Raffles Place at 12.30pm to go to Orchard on some errands.
At City Hall station, he saw a man enter the carriage. The man, who had shoulder-length frizzy brown hair, wore a white T-shirt paired with what "aikido (a Japanese martial art) practitioners" wear when they spar.
"I thought he was wearing a sarong at first," said Mr Ow Yong, who works in a bank.