The deadly fire in Harbin, northern Heilongjiang Province, which killed five firefighters and injured another 14 before being extinguished, may reignite, local fire department said Sunday.

The fire was put out Saturday after burning for over 20 hours. After the collapse of the 11-story building, the blaze's source was buried along with flammable items.

Firemen said it is likely that the fire will reignite and lead to another crumpling since the building's structure is complicated, which makes it difficult to clear the source of the fire completely.

Firefighters have been using water to lower the building's temperature and control the situation from the outside. More than 10 excavators were working to clear the bricks and debris Sunday.

Investigation shows that the fire was caused by an electrical circuit overload. The investigation found that one of the storage rooms, which covers 70 square meters, had used a wooden board to separate the room while wires were exposed.

The overload had ignited nearby flammable plastic items, leading to the fire and the collapse.

The men who were allegedly responsible for the fire were arrested.

The fire has reportedly affected over 2,000 residents and several shops in the building. Five firefighters died and 14 others, including a security guard, were hurt.

The firefighters, who died when the building suddenly collapsed, were aged from 18 to 22. The 18-year-old surnamed Zhao only joined the force in September 2014.

Meantime, the provincial fire and rescue authority stressed that the commander did not order firemen to get inside the building but were only trying to put out the fire from the balcony on the third floor, the only entrance to the building.

He also pointed out that the building was actually a dangerous illegal structure and that the team was unaware of that before the rescue work began.

Li Jin, an expert from a committee under China Fire Protection Association, told the Global Times that fire rescue teams in China are generally young and suffer from a lack of experience.

Li said the firefighters' training in China has been improving in recent years but he hopes it could become more comprehensive and diverse.

"In many mock fire drills, there is a still lack of training facilities. Sometimes, there is no smoke and fire at the training scene," he said.

He also said that authorities should provide more physical training to firefighters such as running, endurance, tactics and the use of equipment to make them more effective at actual fires.

Li's views were echoed by Ma Tingguang, a fire protection and safety technology expert at Oklahoma State University.

Other countries such as Norway have a complete examination system and their firefighters undergo a year-long training, thus minimizing the loss of lives, said Ma, according to Tencent News.