Climate change protesters have blocked the entrance and climbed cranes at the site of a new gas-fired power station.
The Reclaim the Power group said it had "shut down" building work at the Keadby 2 site in North Lincolnshire.
The group claims the new power station would be a "climate disaster".
SSE, which owns the site, said: "Our priority is to ensure the safety of all those on the site and we are working with the police and relevant authorities to resolve the situation."
Humberside Police said a woman had been arrested on suspicion of obstruction of the highway and obstruction of a police officer.
The new £350m power station is being constructed alongside an existing facility near Scunthorpe.
SSE said the new station, which will produce 840MW of electricity, would be "the cleanest and most-efficient gas-fired power station in Europe, displacing less efficient plant from the system, complementing our renewable assets, and safeguarding customers' power supplies."
However, protester Ellie Groves said "new gas spells climate disaster."
"We need clean, cheap, community-controlled renewable power," she said.
The group has also been picketing outside the London offices of Drax, which has a power plant in North Yorkshire.
Speaking at the protest in London, Milo Phillips said: "The government's promises to act on climate change are meaningless while dirty gas power stations are still being built.
"Drax's gas plant in North Yorkshire would be the largest gas power station ever built in the UK."
A Drax spokesperson said gas power stations were needed to "help the UK to meet its climate objectives".
"Natural gas has an important role to play in supporting the growth of renewables like wind and solar, enabling the transition to a net zero carbon economy," a statement from the company added.