Police said the drill was an important step towards check preparedness level of various security agencies ahead of the Independence Day.
"As part of the drill, around 7 PM, four 'armed terrorists' entered Elf Cafe and Bar and took around 12 people 'hostage'. A team of NSG commandos and Delhi police SWAT team arrived at the spot. The NSG team started the rescue operation at 8:35 PM after getting details of the hostages in the restaurant.
During the operation, NSG commandos tackled a possible hostage situation in the restaurant.
We have conducted an anti-terror mock drill with NSG at Hauz Khas Village to check response and preparedness of the police, said a senior police official.