CNN has said it deeply regrets any distress caused by its report on the nursery killings in north-east Thailand, after its footage of the building’s blood-stained floor sparked a police investigation and a debate over how the media should cover such tragedies. The US network’s report, which has since been pulled, was condemned by the Foreign Correspondents’ Club of Thailand and the Thai Journalists Association, while police launched an inquiry over allegations the crew entered the crime scene without authorisation. Deputy national police chief Surachate Hakparn said on Sunday night that officers found the crew had not intended to trespass, though the journalists were fined for working while on a tourist visa. The matter has led to questions over media ethics when reporting on such shocking and highly sensitive tragedies. Thirty-seven people were killed, mostly young children, when a former police officer opened fire and stabbed people in an attack that began at a preschool centre in Uthai Sawan. The attacker then left the nursery, drove his car towards and shot at bystanders, and returned home, where he shot his wife, child and himself. The incident, which took place on Thursday, has horrified Thailand and drawn media attention from across the world. Danaichok Boonsom, director at the Office of Uthai Sawan Municipality, who reportedly filed a complaint to the police in response to CNN’s coverage, told the media: “I want them to be respectful to us. They should not do whatever they want to do or only think about getting their ratings.” The area was in mourning, he added, in comments broadcast by PPTV. “Why do they have to do this? What is it for?” Danaichok’s two-year-old great-nephew was among those killed in the attack. He told the Guardian on Saturday that he was a playful and inquisitive little boy. “He was such a nice kid, very polite. I had a bicycle that I planned to give him,” he said. The Foreign Correspondents’ Club of Thailand said in a statement, released before the police concluded investigations, that CNN should answer a simple question: “Would one of their crews have behaved in the same way at a serious crime scene in the United States?” Allegations the team entered without permission emerged after an image, shared on social media, showed the journalists climbing over a small wall and police tape to exit the nursery. Media associations also said the building had been off-limits to journalists. CNN said the tape wasn’t present when its team entered and that they were given permission by Health Department officials. Had they known that this was not sufficient, they would not have gone inside, a statement from the network said. “We deeply regret any distress or offence our report may have caused, and for any inconvenience to the Thai police at such a distressing time for the country.” The network said its team entered the building to “gain a fuller impression of what transpired inside and to humanise the scale of the tragedy”. However, many questioned the justification. The Thai Journalists Association said that, even if permission was granted, crews and their management “should have exercised their judgment”. The images aired by CNN contained graphic material without a clear appeal to public interest, it said. The Foreign Correspondents’ Club said it was dismayed by the footage. Thailand, it added, has “a difficult history with inappropriate images of violence and abuse in its media” but great strides have been made in recent years to address this problem. There has also been criticism over the number of public ceremonies and photo opportunities put on involving the families of the victims in wake of the tragedy. On Friday, grieving relatives waited at a hall next door to the nursery, where they were handed oversized cardboard compensation cheques by the prime minister, Prayuth Chan-ocha. Some on social media also questioned a decision to roll a red carpet in front of the nursery on Friday morning, ahead of a ceremony in which a royal wreath was placed and families left flowers. It was quickly removed.