Outside, police said a helicopter was nearly struck by a rocket flare set off by protesters. Anothr pilot received eye injuries after a laser was directed at them.
Violent clashes are expected to continue throughout the day with 30 people arrested and more than 100 police injured cars, bins and pallets are set fire to.
Leaders arrived on Friday morning ahead of a day of working meetings on global terrorism and trade, with many holding bilateral talks on the sidelines of the event.
Violent clashes have erupted in the city, with 100,000 protesters expected to appear over the course of the summit. A visit to the Climate Change Research Centre for the leaders’ spouses was called off due to protests, while some online hailed it as a “success” the First Lady was able to get out.
Residents tweeted video of cars in the street set on fire, while Black Bloc protesters marched down the streets elsewhere.
It follows a violent night on Thursday where police used water cannons and tear gas after around 1000 anarchists from the far-left Black Bloc refused to remove their face coverings. Protesters threw rocks and bottles and Hamburg police said they were “appalled” at what had happened.
Anti-capitalist groups set fire to cars, rubbish bins and pallets outside the venue.
The cars of a tyre belonging to a member of the Canadian delegation were slashed while windows at the consulate of Mongolia were slashed.
Police have asked for more reinforcements after the streets proved more violent than expected.
“We have asked nationwide if police forces are available and those requests are being reviewed,” a police spokesman said.