WICHITA, Kan. (AP) — Authorities say the “real work” will start Friday to recover the remains of four people who died when a small plane crashed into a building at a Kansas airport.

Jet fuel from the twin-engine Beechcraft King Air burned so hot after the crash Thursday morning that portions of the building at Wichita Mid-Continent Airport remained unsafe all day.

Wichita Fire Chief Ronald Blackwell says heavy equipment will arrive Friday to remove portions of the building so emergency personnel can reach the victims’ bodies. Crews are expected to be at the site for several days.

A federal investigator says the pilot reported a problem with the aircraft’s left engine soon after taking off from the airport.

Three of the dead were inside the building and the pilot was the fourth victim.