COLOMBO, Sri Lanka (AP) — Gunmen on a motorcycle Thursday shot and killed the editor of a Sri Lankan newspaper critical of the government, the second violent attack on media this week.

Media rights groups have accused the government and its supporters of trying to stifle dissent in the war-wracked country by vilifying journalists seen as critical and creating an atmosphere of impunity for those who attack them.

One of the most outspoken voices belonged to Lasantha Wickramatunga, whose Sunday Leader newspaper has accused President Mahinda Rajapaksa’s government of corruption. Defense Secretary Gotabhaya Rajapaksa, the president’s powerful brother, is suing the newspaper for defamation.

As Wickramatunga drove to work during Thursday’s morning rush hour outside the capital, Colombo, two gunmen rode up and opened fire, police spokesman Ranjith Gunasekara said. Police were investigating, but no one has been arrested.

Television images of the car showed bullet holes in the windshield and blood splattered over the seat.

Wickramatunga was rushed into emergency surgery for nearly three hours but died of head wounds, said Dr. Anil Jasinghe, director of Kalubowila Hospital.

Colleagues said Wickramatunga had received threats recently. In 2007, assailants torched his paper’s printing presses.

President Rajapaksa said in a statement he was “grieved and shocked” by the killing and ordered police to conduct a full investigation.

The media watchdog group Reporters Without Borders, however, said Rajapaksa, other government officials and the state media were partly to blame for the death “because they incited hatred against him and allowed an outrageous level of impunity to develop as regards violence against the press.”

Rajapaksa called Wickramatunga a “terrorist journalist” in an interview with the Paris-based group last October.

“The military victories in the north against the Tamil Tigers rebels must not be seen as a green light for death squads to sow terror among government critics, including outspoken journalists,” the group said in a statement.

The shooting came two days after gunmen armed with assault rifles and grenades raided a private television station and destroyed much of its equipment. No one was seriously injured.

State media had accused the station and its affiliates of not being “patriotic” enough in covering the government’s recent victories over ethnic Tamil separatists in the 25-year-old civil war.

In November, Amnesty International said Sri Lankan journalists face detentions and attacks, with at least 10 media employees killed since 2006 and one missing since being arrested two years ago.

The government has denied it is behind the attacks and has appointed a committee to investigate.