A murder investigation has been launched after the death of a nine-year-old girl at a home in Weston-super-Mare, with a teenage boy arrested on suspicion of murder and remaining in police custody.

Avon and Somerset Police said officers were called by paramedics to a residential address in Lime Close, in the Mead Vale area, at 6.09pm on Monday 15 December. The first officer arrived at 6.12pm. The girl was pronounced dead at the scene.

Police said a teenage boy was arrested in Worle at 6.19pm. He remains in custody on suspicion of murder as enquiries continue. A cordon has remained in place in Lime Close while officers carry out investigative work at the property, with preliminary house-to-house enquiries under way in the surrounding area.

Superintendent Jen Appleford said the town would be “distraught and shocked” by the news. “We know the whole of Weston-super-Mare will be distraught and shocked to learn of this utterly dreadful news,” she said.

Appleford said the girl’s family had been informed and would be supported. “The girl’s family were informed last night of what had happened. It is impossible for us to adequately put into words the pain and anguish they are feeling right now,” she said. “Our heartfelt condolences go out to them, and we’ll ensure they receive support from a specially-trained officer.”

Police said specialist processes are still ongoing. Appleford said formal identification had not yet been completed and a post-mortem examination would be carried out. She asked members of the public not to speculate about the circumstances of the death or those involved. “Out of respect for the family we’d please ask people not to speculate on the circumstances, or the identities of those involved, because that will only add to their enormous distress,” she said.

The force said there would be an increased police presence in the area in the coming days, including additional patrols, as detectives continue to gather evidence and speak to residents. Appleford said officers would be available to provide reassurance and support, adding that police were not aware of any increased risk to public safety. “There will be an increased police presence in the area in the coming days, and we urge anyone with concerns to please speak to us, however we’d like to reassure people we are not aware of there being any increased risk to public safety,” she said.

The scale of the emergency response on Monday evening left nearby residents shaken. One local resident, Glynis Field, told the Guardian that the noise and the number of vehicles were unlike anything she had seen in decades living in the area. “All I heard was the sirens, police sirens, the amount of the police at the back. I’ve never seen so many police cars in all my life, and ambulances, armed police,” she said. “Forty-nine years we’ve lived here, and to think that’s right on our doorstep … it’s awful, terrible, absolutely terrible.”

Detectives typically seek to build an early timeline of events, preserve scenes, recover forensic material, and identify potential witnesses, including anyone who may have been in the area around the time emergency services were called. Police have said enquiries at the property are continuing and that they will provide updates as the investigation progresses, while the cordon remains in place and officers carry out door-to-door checks.

Avon and Somerset Police appealed for anyone with information that could help the investigation to come forward. People were asked to call 101 and quote reference number 5225352036, or use the force’s online appeals form. Police also said information can be passed anonymously to Crimestoppers on 0800 555 111 or through its online reporting service.