About 25 students began a sit-in outside University of Pennsylvania President Amy Gutmann's office Thursday morning in opposition to the Board of Trustees's decision in September not to divest its $10.7 billion endowment from fossil fuels.

The students were denied entrance to Gutmann's office at College Hall but are assembled outside her door, said Peter Thacher, 21, an urban studies major and spokesman for Fossil Free Penn.

Shortly before 9:30 p.m., Thacher, of St. Louis, said the students hadn't seen Gutmann and weren't sure if she was in the office. They are seeking a meeting with her, more "transparency" regarding Penn's decision not to divest and the release of the shareholder voting plan Penn trustees decided to create instead of divesting, Thacher said.

Students plan to stay until their demands are met, he said. Thacher said a rally would be held later on Thursday on College Green.

Penn's trustees and a committee of faculty, staff, students and alumni who studied the issue said fossil fuel investments did not constitute a "moral evil" and therefore did not meet the university's divestment requirement guidelines. The university's investment decisions should not be used for the purpose of making public policy statements, board chair David L. Cohen said.

The university used the same argument when it was asked to divest from tobacco stocks in 2014.

Fossil fuel divestment also has become a controversial issue on some other college campuses around the country.

In 2015, dozens of students at Swarthmore College held a 32-day sit-in, urging trustees to divest the college's $1.9 billion endowment from fossil fuels. They remained in Parrish Hall day and night, but the demonstration concluded without a commitment to divest. The college's trustees in May 2015 voted not to divest.

At Penn, students have been urging the board of trustees to act for more than two years. Undergraduate students have voted in favor of fossil fuel divestment and a letter of support from more than 100 faculty was submitted to the administration.