BANGKOK (AFP) - Three military men were killed and a fourth injured on Sunday in the third fatal Thai army helicopter crash in little over a week, a force spokesman said. The Bell 212 chopper - part of the rescue mission following another helicopter crash on Tuesday - went down in Phetchaburi province, southwest of the capital Bangkok, bringing the death toll from the three incidents to 17. "There were two pilots and two army technicians on board. One was injured and three were killed," Colonel Sunsern Kaewkumnerd told AFP. Thai television news channels showed aerial shots of the flaming wreckage, in the same jungle-heavy province that witnessed the previous tragedies. The aircraft, which was travelling from Bangkok to a task force base in Phetchaburi, had on Saturday transported bodies from a Black Hawk helicopter crash on Tuesday, in which nine people were killed. The victims were eight military personnel and a television cameraman from army-run Channel 5. The Black Hawk was found in dense forest just across the border in Myanmar on Friday morning, three days after it disappeared during a mission to recover the bodies of five soldiers killed in a helicopter accident on July 16. Outgoing premier Abhisit Vejjajiva has said the twin tragedies had a "great impact" on army morale, while a piece in English-language The Nation newspaper on Sunday said they had "cast a veil of gloom over the country". Following the third accident on Sunday morning, army chief General Prayut Chan-O-Cha said that air missions came with added risk, but insisted safety had been a priority. "The first two accidents were caused by bad weather and the third one we presume was an engine problem, but we will wait for an investigation," he said on Channel 3. In the first crash, a Huey helicopter went down in bad weather during a mission to airlift troops from the remote jungle area. It had been sent to collect about 35 soldiers who had been on patrol in the park as part of measures to combat deforestation.