Students beginning classes Tuesday have returned to Porter Ranch Community School in Porter Ranch, Calif., after being displaced for several months because of a large natural gas leak.

The Los Angeles Daily News reports that the entire K-8th-grade school was forced in December to relocate to Northridge Middle School because of a natural gas leak at Southern California Gas Co.’s nearby Aliso Canyon storage facility.

The gas leak has been described as the biggest in U.S. history; it sickened many residents and prompted about 8,000 families to temporarily relocate.

Porter Ranch School officials held a meet-and-greet event over the weekend to welcome students back to the campus.

The gas leak was discovered on Oct. 23, and In mid-December, the Los  Angeles Unified School District decided to temporarily move students to the middle school.

Porter Ranch had lost more than 100 students as a result of the relocation, but now that the home campus has reopened, enrollment now has surpassed previous levels, officials say. The school has been thoroughly cleaned. Each room had to be cleaned and then certified until the entire school was certified, Principal Mary Melvin says.