Ananova:

Fire investigators are to examine the sprinkler system at the warehouse where up to four firefighters died.

Fire officers entered the warehouse in Atherstone On Stour, Warwickshire, on Saturday night, for the first time since Friday night's blaze to make an initial assessment, Warwickshire Fire Service said.

One firefighter has been pronounced dead and three missing firemen are feared dead. A family friend named one of the missing firefighters as Ashley Stephens, 21, of Meadow Road, Alcester, Warwickshire.

A search and rescue team briefly entered the collapsed building on Saturday night, after colleagues finished damping down. The team spent just a few minutes inside the fire-ravaged vegetable packing warehouse, only managing to make it a few feet inside, before withdrawing for the night, the fire service said.

Structural engineers and the Health and Safety Executive are to join them when they return to the scene.

Crews were alerted to the fire at about 6pm on Friday and more than 80 firefighters battled the flames into the early hours of Saturday morning.

Missing firefighter Mr Stephens lived with his mother Kerry, older brother Paul and younger sister Sharon. According to Mr Stephens' page on the social networking site Bebo he was engaged to 17-year-old Emma Crocker and became a father on August 1.

The young firefighter has a number of pictures of his fiancee and his three-month-old son George Stephens on his website. He describes himself as a "full-time joiner and a retained firefighter", and says he hoped to be accepted as a full-time firefighter one day.

The Fire Brigades Union (FBU) said all four were part-time retained firefighters and pledged to look at all health and safety issues relating to the tragedy. The tactics firefighters used to tackle the blaze will be investigated, Warwickshire's Chief Fire Officer, William Brown said.

Warwickshire Police said the fire would be treated as suspicious until its cause was established and appealed for witnesses.