The SFPD arrested the man in the trailer, who was later identified as 32-year-old Thomas Siderio of Philadelphia. He was booked into jail on suspicion of distributing nitrous oxide and possessing nitrous oxide "with intent to ingest for toxication," police said.

A Philadelphia man was arrested on suspicion of possessing about 100 tanks of nitrous oxide outside Golden Gate Park, San Francisco police said.

Fans of the Grateful Dead are pouring into San Francisco for three days of concerts and festivities marking the 60th anniversary of the scruffy jam band that came to embody a city where people wore flowers in their hair and made love,