While searching the abandoned compound: none of the police officers has a radio.
Lena lays in her hospital bed for hours with untreated injuries.
From 23:28 -the local police are unaware that there exists "a decommissioned military compound" located, basically, in their own backyard.
It is not explained how Hannah was able to acquire the piece of broken glass and smuggle it into the hospital to give to Lena.