A massive explosion at a UK fireworks factory injured at least five people on Thursday evening, with emergency service responders attempting to control the intense blaze in Tilcon Avenue, Stafford, police said.

A dramatic scene, with fireworks shooting out of the building and thick plumes of black smoke could be seen in several online photographs of the blaze. The cause of the incident remains unknown, The Guardian reported.

While two victims were rushed to the major trauma center at University Hospital North Staffordshire, other patients suffering from burns and smoke inhalation were being treated by four ambulance crews, West Midlands Ambulance Service said, which had also sent the Hazardous Area Response Team, four emergency doctors, five paramedic officers and two rapid response vehicles to the scene.

"Two patients are being taken to the major trauma center at University Hospital North Staffordshire. One has burns, the other has smoke inhalation. Two further patients have been discharged on scene. A further patient has minor injuries," a spokesman said.

Around 5:15 p.m. Thursday, local residents reportedly heard a "loud bang" and then saw smoke emanating from the factory premises, prompting authorities to issue a warning for people in the Baswich area to shut their windows and stay indoors, according to Sky News.

"A cordon is in place to protect the public and we are urging those in the area to remain indoors with windows closed," Staffordshire Fire and Rescue Service said, describing the blaze at the industrial unit as an "escalating fire" that was still attempting to be controlled by eight fire engines.

"Large fire in industrial unit well alight. Trains running under caution nearby. Stay indoors and keep windows shut," a spokesman stated.

Onlooker Mike Hillman said he was watching from Tixall Road, adding "massive fire, loads of smoke this way, hope everyone is OK".

"My friend said 'Oh, something has fallen on my head'. It turned out to be ash falling on us. As we got closer the smoke got worse and worse. You could just hear explosions and fireworks going off," another onlooker Christina Harrison told BBC News.

"I did see some fireworks going off but not much in the way of that."

Meanwhile, several roads have been closed off and police are evacuating a number of homes in the area after five businesses, including a roof collapse, were reported have been affected, according to local newspaper reports, UK MailOnline reported.