BERLIN (AP) — Authorities in Germany on Friday were reviewing security measures at Berlin's airport a day after six climate activists invaded the grounds and briefly disrupted flights.

German news agency dpa quoted a spokesman for Berlin Brandenburg Airport saying that Thursday's incident was being reviewed to determine what further action may be required.

Police said four protesters glued themselves to the ground near the runway, while two others cycled across the premises. The group Uprising of the Last Generation, which has staged numerous road blockades and other stunts to highlight the need for action against climate change, claimed responsibility.

The group said it wanted to highlight the problem of fossil fuel subsidies, such as for jet fuel, which allow a minority of the world's population to fly while the majority suffer the consequences of climate change stoked by greenhouse gas emissions.

It said the activists notified police of their plans before entering the airport grounds.

The protest was widely criticized by German lawmakers across political lines, though Martin Schirdewan, co-leader of the Left party, said the activists had “put their finger on the wound of political inaction in view of the climate catastrophe.”

Police said five men and one woman aged between 20 and 32 were detained. Five people were released, while the sixth remains in custody. All six are being investigated on suspicion of endangering air traffic, property damage and trespassing.

Airport authorities said 15 planes had to be diverted to nearby airports while five departures were delayed. About 750 passengers were affected by the disruption, it said.

Earlier this month, hundreds of climate protesters blocked private jets from leaving Amsterdam’s Schiphol Airport.