The Pentagon
On 11 September 2001 , American Airlines Flight 77 was hijacked and flown into the western side of the building , killing 189 people . 
<triplet> 11 September 2001 <subj> 11 September 2001 <obj> point in time <subj> hijacked <obj> instance of <triplet> American Airlines Flight 77 <subj> 11 September 2001 <obj> point in time