A man armed with a rifle and a handgun killed four people inside a medical complex in the US city of <a href="https://www.thenationalnews.com/opinion/comment/on-centenary-of-the-tulsa-massacre-america-must-confront-history-1.1240901" target="_blank">Tulsa in Oklahoma</a> on Wednesday before shooting himself dead, police said. It is the latest of a series of mass shootings in the US and came on the same week that the city of <a href="https://www.thenationalnews.com/world/us-news/2022/05/31/texas-town-begins-funerals-for-children-killed-in-uvalde-school-shooting/" target="_blank">Uvalde, Texas</a>, began burying those killed in the deadliest primary school shooting in nearly 10 years. Police arrived at the St Francis Hospital campus three minutes after receiving a call about the shooting on Wednesday afternoon and followed the sound of gunfire up to the Natalie Building's second floor, Tulsa deputy police chief Eric Dalgleish told reporters. Officers made contact with the victims and the suspect five minutes later. Police responses have come under increased scrutiny after a <a href="https://www.thenationalnews.com/world/us-news/2022/05/25/at-least-19-children-and-one-adult-killed-in-texas-school-shooting/" target="_blank">gunman killed 19 children and two teachers in a Texas school classroom</a> last week while officers waited outside for nearly an hour. Asked by reporters whether police had refreshed training or thinking about active gunmen after the school shooting, Mr Dalgleish said: “I think that's probably fresh on everyone's minds. “I will say Tulsa revisits that topic regularly. I was very happy with what we know so far regarding the response of our officers.” Wednesday's incident in Tulsa came on the heels of mass shootings that have reignited debates about US gun control. Two weeks before the Uvalde shooting, <a href="https://www.thenationalnews.com/world/us-news/2022/05/19/buffalo-shooting-grand-jury-indicts-suspected-gunman-on-murder-charge/" target="_blank">a white gunman killed 10 people at a supermarket in a black neighbourhood in Buffalo</a>, New York. “What happened today in Tulsa is a senseless act of violence and hatred,” Oklahoma Governor Kevin Stitt said. Police in Tulsa said they were trying to determine the identity of the gunman, whom they estimated was 35 to 40, and had no details yet on his motive. No explosives were found during a search at a residence in Muskogee, Oklahoma, local media reported, citing police. The home is still the subject of an investigation. The Natalie Building contains doctors' offices including an orthopaedic centre, Mr Dalgleish said. He said he believed the victims included employees and patients. “This campus is sacred ground for our community,” said Tulsa Mayor GT Bynum. “For decades, this campus has been a place where heroes come to work every day to save the lives of people in our community. “Right now, my thoughts are with the victims. If we want to have a policy discussion, that is something to be had in the future, but not tonight.” The White House said President Joe Biden had been briefed on the shooting and offered support to state and local officials in Tulsa, a city of about 411,000 people that is 160 kilometres north-east of state capital Oklahoma City. Since January, there have been 12 mass shootings in the US that have left at least four people dead, according to the <a href="https://www.gunviolencearchive.org/reports/mass-shooting?sort=desc&order=%23%20Killed" target="_blank">Gun Violence Archive</a> database. <i>Agencies contributed to this report</i>