Phnom Penh, Cambodia (CNN) -- Cambodian security forces fired on garment workers protesting in the country's capital Friday, killing at least three people.
The workers, who have been demonstrating since last week to demand higher wages, clashed with riot and military police outside the Canadia industrial park in southwestern Phnom Penh, where many garment factories are located.
Protesters threw rocks, used slingshots and made improvised barricades by amassing scrap in the middle of the road and lighting it on fire.
Security forces responded with live ammunition rounds, witnesses said. Gunfire rang out in the area.
Chuon Narin, Phnom Penh's deputy police chief, said three people were killed and two others wounded in the clashes.
But a local human rights group, Licadho, said it believed that at least four people were killed and dozens more were injured.
The United Nations Special Rapporteur on the situation of human rights in Cambodia, Surya P. Subedi, said four people were reportedly killed.
"I am deeply concerned at the latest clashes in Cambodia and deplore the loss of life," Subedi said in a statement. "I call on the authorities to exercise restraint towards protestors. Any use of force by officials must be subject to the principles of legality, necessity and proportionality."
He also called on protesters to show restraint.
Chan Dy, a garment worker in the industrial park, said he was "very worried because many workers were injured."
At the Khmer-Soviet Friendship Hospital, where some of those hurt were brought, Dr. Chin Kosal in the intensive care unit said staff members were treating six gunshot victims and one other wounded person.
Lying on a bed in a bloodied shirt, Keat Rady, 20, said she was cheering along with protesters in the street Friday morning when a bullet came from above and hit her on the left side of her upper chest, traveling through the flesh and into her left arm.
Scores of people were reported to have been arrested as police continued to break up the demonstrations.
The garment workers are striking to demand an increase in their minimum wage from $80 to $160 a month. They have rejected the government's offers of $95 and $100.
Protests are frequent in Cambodia's important garment industry, which is estimated to employ 400,000 people and account for roughly $5 billion in exports.
Some scuffles had taken place during the strikes, but the situation escalated Thursday when several protesters were arrested.
The International Labor Organization this week urged the parties involved to use dialogue to resolve the dispute.
The protests are fueled by the wage issue but are supported by the opposition Cambodia National Rescue Party, which has recently been leading large-scale marches and demonstrations against the government in the capital.
The opposition claims that it was cheated out of crucial votes during July's national elections, which were won by long-serving Prime Minister Hun Sen's Cambodian People's Party.
Journalist Joseph Freeman reported from Phnom Penh, and CNN's Jethro Mullen reported and wrote from Hong Kong.