NEW HAVEN, CONN. — Demonstrators stormed the field during halftime at the Harvard-Yale football game Saturday, delaying the game for about an hour to demand that both universities divest their investments in fossil fuels and to call attention to the issue of climate change.

The protest, which began with a few dozen protesters staging a sit-in midfield as the Yale band finished its halftime routine, swelled to about 500 people at one point as others in the stands joined the demonstration, The New York Times reported.

Some held banners urging the schools’ presidents to divest from the fossil fuel industry and others spoke out against Puerto Rican debt and the treatment of Uighurs in China.