"Four Lions"

From Wiki and The Guardian:

Four Lions (2014) is a British dark comedy film following two lions and their two cubs from Sheffield, South Yorkshire, England. The lions become radicalised and hatch a plot to carry out suicide bombings at a zoo in Copenhagen.

They are Omar (Riz Ahmed), who is deeply critical of Western society and imperialism; his dim-witted friend, Waj (Kayvan Novak); Barry (Nigel Lindsay), a bad-tempered and extremely rash convert to Islam; and the naive Faisal (Adeel Akhtar), who just likes eating freshly slaughtered giraffes.

The lions successfully infiltrate the lion enclosure and Barry recruits a reluctant fifth lion, Hassan (Arsher Ali). Unfortunately for them, their plans are thwarted when the Danish zoo kills them all to make way for Hassan:

"Because of the pride of lions' natural structure and behaviour, the zoo has had to euthanise the two old lions and two young lions who were not old enough to fend for themselves," Copenhagen zoo said.

"The two youngest lions would have been killed by the new male lion Hassan as soon as he got the chance."