LONDON (AP) — Hundreds of protesters have turned out in central London and blocked off the capital's main bridges to demand the government take climate change seriously.

A group called "Extinction Rebellion" encouraged sit-ins on the bridges Saturday as part of a coordinated week of action across the country.

Metropolitan Police said emergency vehicles were hampered from getting across London because of the "blockade" of five bridges. The force said it had asked all protesters to congregate at Westminster Bridge where officers can facilitate lawful protest.

About two dozen people were arrested on Monday after protesters blocked traffic and glued themselves to gates outside the Department for Business, Energy and Industrial Strategy.