Students unveiled a tribute to fallen officer Sean Collier at Massachusetts Institute of Technology on Friday as thousands of hanging paper cranes were displayed in an atrium at the institution.

According to the project’s Facebook page, thousands of paper cranes were contributed by students, faculty, alumni, and many others from the area. The site said:

Thousands of cranes were individually strung and glued onto thin threads; together, they were suspended from a large hoop underneath the circular skylight in that lobby. As a result, the cranes float together in a column.

Collier was shot and killed on campus by the alleged Boston Marathon bombing supects while sitting in his car on duty on April 18, 2013.