He used a public bus as his getaway vehicle - until a dye pack exploded in his jacket.

St. Petersburg, Florida -- A man with a pockmarked face and thick glasses robbed a Wachovia bank branch today.

Police said he made his escape on a public bus but got off and ran when a red dye pack, stashed with the cash, exploded inside his jacket.

The robbery occurred mid-afternoon at the bank branch at 125 Fifth Street South. Police said he gave a teller a note threatening harm if she did not hand over money. She complied, but included a dye pack with the cash.

The suspect left the bank but was spotted on a public transit bus when the dye pack exploded inside his jacket. He got off the bus and ran, police said.

The suspect is described as a white male, in his 50s, about 5'9" tall, slender build, with deep pock marks on his face and large brown framed glasses with tick lens.

He was wearing dark pants, a tan baseball cap with blue trim and a blue bandana underneath, and a gold or beige jacket -- now stained with a red dye.

Anyone who recognizes him is asked to contact St. Petersburg Police Det.  Michael Hawkins (727) 893-4978 or the main Robbery Unit at (727) 893-7179.