An Unknown Mystery

Part 1
A passenger plane flew over Sarajevo, Bosnia & Herzegovina. the pilot felt something suspicious on the city below.

So here is the full script:
PILOT: We are now closing in for the runway.

SJJ CONTROL TOWER: You are about 30 miles from the runway. and what about the altitude?

PILOT: Our altitude is about 1-4-5 (14,500 miles, or about 233 km high) above East Sarajevo.

CONTROL TOWER:Anything suspicious?

PILOT:Yes, I saw a large crowd from the cemetery heading for the city proper.

CONTROL TOWER: So what is it?

PILOT:I don't know.