One person was killed and about 15 were wounded when Sri Lanka’s military shot at a protest demanding clean drinking water.

At least 4,000 protesters had gathered on Thursday in Weliweriya, some 12 miles (20 kilometres) northeast of the capital, Colombo. A protester who spoke on condition of anonymity, fearing reprisals, said chemical emissions from a factory into water sources has polluted drinking water in about 15 area villages.

Residents have been demanding for more than a month that authorities close down the factory but to no avail, the protester said.

Reporters said soldiers beat up several reporters and photographers who were covering the incident and smashed their cameras.

Kanchana Dissanayake, editor of Sinhala-language “Ada” (Today) newspaper, said that his photographer was admitted to a hospital after being beaten by soldiers. He claimed the soldiers said that “media dogs” should not cover the protest and smashed his camera.

Another female reporter said on condition of anonymity fearing reprisals that soldiers first targeted journalists because they wanted the media away before turning on the protesters. Many reporters were hiding for many hours into the night, she said.

Police spokesman Buddika Siriwardene said one person died and 15 were hospitalized but declined to comment on the nature of the injuries.

Siriwardene said the situation arose because protesters continued to block a main road, obstructing traffic, despite agreeing with the defence ministry to call off demonstrations until investigations are complete.

Thursday’s incident is the third in two years in Sri Lanka where police or military have used firearms on public protests. In 2011 a factory worker was shot dead during a demonstration, and in 2012 police shot and killed a fisherman who was protesting against rising fuel prices.