A number of people have been injured in an ongoing incident in Rhondda Cynon Taf, police have confirmed.
South Wales Police said officers were dealing with “a serious incident” which happened in Baglan Street, Treorchy, at about midday on Friday.
The force said the street has been closed off and people were advised to avoid the area until further notice.
Ambulance crews are also in attendance as the incident involves a number of casualties.
South Wales Police has also urged the public to “refrain from speculation” about the incident.
A spokesperson from the Welsh Ambulance Service said it was called today at 12:00 GMT “to an incident at an address in the Ynyswen area of Treorchy”.
“We attended the scene with one rapid response vehicle, three emergency ambulances, our hazardous area response team and the Wales Air Ambulance.”
Rhondda MP Chris Bryant tweeted that he was aware of “disturbing events on Baglan Street” and said his thoughts go out to all those affected.
He also said that primary school Ysgol Gynradd Gymraeg Ynyswen is “aware of the incident and have taken all necessary precautions”.
Andrew Morgan, leader of Rhondda Cynon Taf council, tweeted his thanks to emergency services for “the significant attendance which is ongoing”.
“The main street through Ynsywen is sealed off, there are a good number of police officers, there are forensic officers in white suits examining the area surrounding a Chinese restaurant called The Blue Sky.
“I overheard one officer saying to a member of the public he had never seen so many police officers and emergency vehicles at one time.
“As I was driving here I saw two ambulances being escorted by police vehicles at speed, moving down through the Rhondda.”
A Wales Air Ambulance landed in Ynyswen at 13:00 GMT from Mid Wales Airport in Powys.
South Wales Police urged anyone who may have witnessed the incident to contact the force.