Firefighter Rennysa Ithnin does more than dash into burning buildings to put out flames.

Two years ago, she rescued two young children, aged two and five, who were trapped in a locked car in a multi-storey carpark after their father left the keys inside.

"The father and his boys were all crying when we arrived. I could hear the boys shouting for help," recalled the 37-year-old.

At the time, her mind flashed to her two young daughters at home, but she had to act quickly.

She smashed the car window and carried the children out, careful not to hurt them in the process.

"No parent would want to be separated from their children. It was sad to see the father in tears. Later, he was very grateful."

Rising through the ranks, she became a senior instructor at the Civil Defence Academy last year and now has at least 30 trainees under her at a time. This is a far cry from her days as a slightly overweight and shy teenager, fond of staying indoors in front of the TV.

After completing her diploma in mechatronics, she decided to join the Singapore Civil Defence Force (SCDF) just over 12 years ago.

Before she began her six-month training in 2002, she rarely exercised. But, as the only female trainee in her batch, she received plenty of support from the male trainees, who went on runs with her every weekday evening.

In three months, she was able to pass her Individual Physical Proficiency Test and, in 2006, was picked for a specialist course in hazardous materials. These specialists are trained to detect and contain hazardous chemicals and toxins.

Although the number of female firefighters remains small, standing at about 40 now, she has never once felt that her gender was a disadvantage. "As long as you have the endurance and perseverance, you can make it. We are no different from male firefighters."