Hoping to increase their current winning streak the Titans flew to Qualcomm Stadium for an AFC duel with the Chargers. In the first quarter the Titans took the lead when the Chargers' punt was blocked by Nick Schommer out of bounds for a safety. The Chargers replied with FB Mike Tolbert getting a 1-yard TD run. The Titans went on a scoring rally with kicker Rob Bironas nailing a 21-yard field goal, followed in the second quarter by QB Vince Young completing a 1-yard TD pass to TE Craig Stevens. They increased their lead with RB Chris Johnson getting a 29-yard TD run. The Chargers went on a scoring rally with RB Ryan Mathews making a 7-yard TD run, followed in the third quarter by kicker Kris Brown making a 34-yard field goal. Then QB Philip Rivers completed a 48-yard TD pass to TE Antonio Gates, and then Brown made a 36-yard field goal. The Titans tried to come back with Young finding WR Nate Washington on a 71-yard TD pass (with a failed 2-point conversion), but couldn't do anything after Rivers got a 13-yard TD pass to RB Darren Sproles.

Answer this question based on the article: How many field goals were kicked in the second half?
2