A team of high-school students won a 24-hour city-hosted hackathon in Los Angeles this weekend for creating an app that helps volunteer groups identify what homeless shelters need. The event was hosted at City Hall in conjunction of the launch of a new open data portal for the city.

The four high school students split a $3,000 prize for their app, which allows shelters to report what they need so restaurants and volunteer groups can donate the right things. About 30 teams competed in the app contest, the theme of which was civic engagement.

Other apps to come out of the contest included one that allows business owners who want murals to connect with artists who want to paint murals, an app for finding someone to bike home with, a mapping app that tracks city planning permits over time, an app that tracks crime data over time, and an app that tracks linguistic trends on Twitter.

Second place in the hackathon went to the creator of an app that allows people to report water wastage like broken sprinklers.

The hackathon was part of a larger conference held at City Hall. More than 1,500 people registered for the event, which featured seminars on big data, self-driving vehicles and the digital divide.