Students at SDSU held a candlelight vigil for the exchange student on Monday at 6 p.m. on the free speech steps next to the school's Aztec Center.
Organizers called it an opportunity for everyone to come together to support Austin Bice, 22, and his family in their time of need.
"We are just gathering the community, friends and people who want to express support," said Rev. Darin Johnson, campus pastor for the Agape House campus ministry at San Diego State.
The organization expected to have more than 200 people at Monday night's event. The ministry handed out candles.
The group also planned to hand out red and black ribbons with Bice's name imprinted on them during the vigil.
Bice has been studying for the last semester in Spain. A Madrid newspaper reported that bouncers refused Bice entry into the club because he appeared to be too intoxicated. Friends say he didn't go into a nightclub with his friends and decided to walk home.
However, a friend now says, police now believe the last time Bice was seen was at a fast food restaurant.
Family and friends have hired a private company called the Halo Corporation, comprised of former special operations military and intelligence personnel. The company's efforts in retrieving people who are abducted or kidnapped have been featured in a television show on the Discovery Channel.
The family was accepting donations at Monday night's vigil to help fund the Halo Corporation's search efforts in Spain.