COLOGNE, Germany (CNN) -- Two people remained missing in the rubble of an archive building that collapsed in Cologne's city center, a spokesman for the city's fire department said Wednesday.
CNN iReporter Andreas Gress says he couldn't get near the building after work on Tuesday.
The two missing men were in a residential building next to the archive building when it collapsed Tuesday afternoon. The building they were in was heavily damaged by a second building that collapsed, spokesman Stefan Besslich said.
One person in that adjacent building was injured, he said.
Authorities haven't yet determined what brought down the structure, which housed the city's historical archive, with records going back 1,000 years, Besslich said.
With rain forecast for Wednesday afternoon, Besslich said authorities were working to cover the building so the records were kept dry. They are also starting the task of removing the records to keep them safe, he said.
"It's still too early" to speculate on the cause, Besslich said. "The search for people is an absolute priority (and) the covering of the building is an absolute priority." iReport.com: See photos of the rescue scene
The fire department confirmed that everyone in the archive building managed to escape before the collapse of the structure.
The city is building a new subway line under the buildings that collapsed, Susanne Motter at the Cologne tourism bureau told CNN.
But Gudrun Meyer, a spokeswoman at the Cologne Transportation Department, said construction was not taking place below the collapsed structure.