A murder investigation has been launched after two teenage boys were killed in a stabbing attack in Bristol that may have been witnessed by passengers on a bus. The boys, aged 15 and 16, were fatally stabbed in Ilminster Avenue in Knowle West, south Bristol, at about 11.20pm on Saturday, Avon and Somerset police said. The force described the attack, by a group who fled the scene in a car, as “shocking and tragic”. It confirmed that a murder investigation had been launched. A 44-year-old man and a 15-year-old boy have been arrested and are in custody and a vehicle has been seized. The police are hunting further suspects, according to the Bristol area commander, Supt Mark Runacres, who is leading the investigation. Speaking at a press conference near the scene on Sunday, he said: “There are further suspects that are being sought amongst the group that we believe are responsible. There’s certainly other suspects that are involved in the incident beyond the two that have been arrested so far.” He said it was unclear at this stage whether the attackers knew the victims. Runacres appealed for any witnesses to come forward, particularly if they were among those travelling on a bus on Ilminster Avenue at the time of the stabbings. He said officers wanted to “speak to people who were on that bus to see if they can provide any information, to see if they’ve seen anyone in the vicinity that can help us with our inquiries”. He said: “An incident like this is horrific in nature. It causes real distress and upset to all within the community. It make you feel deeply upset [and] frustrated that offences like this will take place anywhere. It’s demoralising. But it makes me determined to support the community [and] work with the team of police officers that we have committed to this to identify those [responsible] and bring them to justice.” Formal identification of the victims and a postmortem are due to be carried out. Liaison officers would be assigned to support the families and update them on the investigation, police said. Police arrived at the scene within minutes of the attack and administered first aid. The victims were taken by ambulance to two hospitals, Southmead hospital and Bristol Royal hospital for children, where both died early on Sunday morning. An Avon and Somerset police statement said: “This is an incredibly shocking and tragic incident where two young boys, who had their whole lives ahead of them, have sadly died.” A mobile police station was to be set up near the scene to take witness statements and gather CCTV and doorbell footage. A vigil was held on Sunday night at which one resident told how she held one of the victims in her lap as emergency services raced to the scene. Julie O’Reilly was one of about 150 people in attendance. She said: “I was there. I went out to the young chap on the floor – I went out to him. I had his head on my lap. Trying to tell him: ‘Stay with us, stay with us – we’ve got help coming.’ That was last night. [Today has been] awful. I can’t get it out of my head. He was a good boy.” Another local, Rianne, said: “It’s shocking, really sad – but you’re expecting to wake up to something these days. I don’t know the families – I’m in the community, but I don’t know the families. But I’ve got kids myself. I’ve just been in a right state. My kids have got to grow up around here.” The vigil was organised on social media on Sunday afternoon. Dozens of floral tributes were left, candles lit and a minute’s silence was observed. One woman said, “Enough is enough” as she addressed the crowd and urged parents to take a tougher stance on crime in the area. Runacres urged the public not to speculate or share images linked to the killings online. He said: “It is extremely important there should be no commentary or sharing of information or images online which could in any way prejudice and any future proceedings. It can be an offence to identify anyone who witnessed all or part of the incident as well as those who have been arrested. “I’d also like to remind people of the impact the sharing of images, footage or even discussing the incident online may have on the families of the two boys. They are already going through the most difficult of times and you may cause them further upset.”