Mr Wickramatunga died of head wounds
The editor of a Sri Lankan newspaper often critical of the government has been shot dead in Colombo.
Police say Sunday Leader editor Lasantha Wickramatunga was shot by unidentified gunmen on motorcycles as he drove to work in the city suburbs.
He died from head wounds after nearly three hours of surgery, doctors say.
Correspondents say Mr Wickramatunga had numerous run-ins with the government. It is the second major attack on the media in Sri Lanka this week.
On Tuesday, gunmen armed with grenades ransacked offices of the largest private TV broadcaster in the country.
Journalists in Sri Lanka have suffered a string of recent attacks and media freedom groups say intimidation and violence make it one of the most difficult countries in the world in which to report.
Amnesty International said in November that at least 10 media employees had been killed in Sri Lanka since 2006.
Some reporters say the intimidation has got worse as the war has intensified with the Tamil Tigers.
The BBC's Roland Buerk in Colombo says the government has been accused of encouraging the violence, by branding reporters seen as critical rebel-sympathisers and enemies of the state.
Sri Lanka's government has condemned the incidents and ordered full police investigations.
Television pictures of Mr Wickramatunga's car showed blood-stained seats and bullet holes in the windscreen.
"We tried our best to revive him but we couldn't," hospital director Anil Jasinghe told the AFP news agency.
Police spokesman Ranjith Gunasekera said gunmen on two motorcycles had escaped after carrying out the attack. No arrests have been made.
Police are investigating the attack
President Mahinda Rajapaksa said in a statement he was "grieved and shocked" by the killing and ordered police to investigate.
The campaigning group Reporters Without Borders said: "Sri Lanka has lost one of its more talented, courageous and iconoclastic journalists.
"President Mahinda Rajapaksa, his associates and the government media are directly to blame because they incited hatred against him and allowed an outrageous level of impunity to develop as regards violence against the press."
Mr Wickramatunga, 52, had been highly critical of government policy and the war with the Tamil Tiger rebels. He received numerous death threats through his career and was detained on several occasions because of the controversial nature of his stories.
In his last editorial he accused the president of pursuing the war to stay in power.
Critics say press freedom is under attack in Sri Lanka
"Winning the war? Then there must be elections around the corner. It is no secret that the war has become Mahinda Rajapaksa's recipe for electoral success," he wrote.
He also criticised opposition parties for staying "mute", suggesting journalists were having to do their job for them.
"That is why more journalists have been attacked in recent years than have opposition politicians," he said.
Mr Wickramatunga's death follows Tuesday's attack on the MBC group in Colombo. He worked for the channel as a presenter on a weekly current affairs programme.
MBC had been criticised by the government for its coverage of the war against the Tamil Tigers.
More than a dozen intruders held guards at gunpoint and shot up equipment, causing extensive damage.
The anti-establishment Sunday Leader has regularly sent up the country's politicians and its editor had fought a number of libel cases.
He was prosecuted for criminal libel of President Chandrika Kumaratunga in 2000, but escaped serious punishment.
Correspondents say that while some of his stories verged on the salacious, others exposed high-level corruption - he recently reported on an arms procurement deal with Russia in which it was alleged that government ministers were receiving financial "kick-backs".
Defence Secretary Gotabhaya Rajapaksa, the president's brother, is currently suing the paper for defamation.