Le Thi An of Kim Dong District is being investigated, the local police said Thursday.

If found guilty, she could be jailed for one to five years.

On April 3, the boy, who has not been identified, was attacked by a pack of nine dogs while returning home from a local gymnasium.

He was admitted to the Hung Yen General Hospital with profuse bleeding, dilated pupils and a stopped heart. He later succumbed to his wounds.

A man who tried to save the boy, who has also not been identified, said: "The boy was attacked at around 6:30 p.m. when it was dark and he was far from home, with few people around. When I discovered what was going on, I called two others with me to use bricks and sticks [to chase away the dogs], but it took five minutes. By that time the boy was severely bleeding and wounded."

Locals said An frequently let the pack loose and they have attacked people in the past too. She had been told to either keep them inside or muzzle them, but she ignored the demands, they said.

An claimed to be distraught at what happened.

Two days after the tragedy, she said: "I couldn’t sleep because of remorse. I loved the boy and did not know what was going on."

The dogs are being held at a police station.

Cases of lethal attacks by dogs on humans are not uncommon in Vietnam. Last month an 11-year-old boy in the northern province of Son La died after being bitten three months earlier by a dog.

Last February a father and son died of rabies two months after being bitten by a pet dog.

Vietnam last year passed a law requiring dogs to be muzzled and chained in public. Violations can cost the owners VND600,000 ($26) to VND1.6 million ($71).

Several cities have hired dogcatchers, including Saigon and Hanoi.