They were about to swim at a condominium pool when they saw a maid and another woman waving at them for help.
"I thought they were just asking us to help pick something up from the water," said Miss Louisa Tay, who lives at Evergreen Park condominium in Hougang.
But the 21-year-old student was shocked to see her boyfriend, full-time national serviceman Kenneth Tan, dive to the bottom of the 1.5-metre- deep pool and emerge with a young girl in a pink swimsuit.
Mr Tan, who was visiting Miss Tay on his day off, swam almost the entire length of the pool to reach the drowning girl.
The incident happened at around 4pm on March 27, and Mr Tan's act of courage was posted on the Singapore Army's Facebook page on Wednesday. (See report at top.)
The corporal told The New Paper yesterday that he had only one thought on his mind - to get the girl out of the pool as quickly as possible.
The girl, believed to be about seven years old, was unconscious by then.
"She wasn't moving the whole time," he said.
Mr Tan immediately performed cardiopulmonary resuscitation (CPR) on her.
"It was my first time encountering something like this, so I felt nervous. But saving her life was my priority," he said.
After a few rounds of chest compressions, Mr Tan performed mouth-to-mouth resuscitation.
It was then that she regained consciousness, and started to cough and spit out water.
"The scene was quite chaotic. The maid kept screaming for help, so the atmosphere was tense," Mr Tan said.
Miss Tay said that the girl had been in the pool for about two minutes and it took about five minutes for her to be revived.
"After some time, she started to cry loudly and kept crying even after my boyfriend and I left," said Miss Tay.
The couple were invited to dinner by the girl's parents last Saturday.
Miss Tay said the mother told her that the girl was giddy and unusually quiet when they got home after her close shave.