Hoping to snap a two-game losing skid, the Steelers went home, donned their throwback uniforms, and prepared for a Week 4 Sunday night duel with the San Diego Chargers. Pittsburgh got off to a fast start in the opening half with running back Rashard Mendenhall (filling in for the injured Willie Parker) helping out the cause on a 1-yard touchdown run in the first quarter, followed by quarterback Ben Roethlisberger's 19-yard touchdown pass to running back Mewelde Moore.  The Steelers would carry their fast start into the second quarter as Mendenhall got a 2-yard touchdown run. In the third quarter, Pittsburgh picked up where they left off with Roethlisberger completing a 6-yard touchdown pass to tight end Heath Miller.  The Chargers would get on the board with quarterback Philip Rivers' 3-yard touchdown pass to tight end Antonio Gates.  In the fourth quarter, San Diego began to play catch-up with a special teams play. Fullback Jacob Hester would strip return specialist Stefan Logan of the ball and go 41&#160;yards for a touchdown. The Steelers came right back with a trick play, as Moore completed a 6-yard touchdown pass to Miller. However, the Chargers would slash away at the Steelers' lead with Rivers completing a 30-yard touchdown pass to Gates and a 13-yard touchdown pass to wide receiver Chris Chambers. Pittsburgh would answer the call with kicker Jeff Reed booting a 46-yard field goal, followed by linebacker James Harrison causing a sack and a fumble. It would allow linebacker James Farrior to recover the fumble and secure the victory. With the win, not only did the Steelers improve to 2-2, but they also extended their regular season home-game winning streak over San Diego to 13-straight. Mendenhall would have a career night with 29 carries for 165&#160;yards, in addition to his two rushing touchdowns.
Question: How many first quarter touchdowns did the Steelers score?
Answer: 2