After losing the previous week to Jacksonville, the Indianapolis Colts came back home to Lucas Oil Stadium to battle with an undefeated Kansas City Chiefs team.  The Chiefs' head coach, Todd Haley opened up the ballgame with an onside kick intended to give Kansas City the ball first.  However, after it bounced less than 10&#160;yards, the Colts received possession deep in Kansas City territory.  Indianapolis was unable to capitalize on the good field position and forced Adam Vinatieri to kick a 20-yard field goal.  Throughout the first quarter neither teams' offenses were able to get into a rhythm and by the end of the first quarter the Colts held a slim lead by the score of 3-0.  With the start of the second quarter the offensive woes continued.  The Colts were again unable to score a touchdown on good field position and were forced to kick their second field goal of the day.  After a failed running play of fourth down by the Colts, the Chiefs were able to move down the field on good passes by Matt Cassel and a penalty on the Colts and were able to kick a field goal. Going into halftime, the score was 6-3 Colts.  The third quarter continued to prove to be a defensive struggle.  The Colts kicked another field goal midway through, however the Chiefs drove down the field to score another field goal.  A Peyton Manning interception set up another field goal by the Chiefs which tied the game at 9-9.  At the beginning of the fourth quarter the Colts continued their scoring ways of the day with a fourth field goal from Vinatieri.  Finally with four minutes left in the ballgame, Mike Hart broke open an 11-yard run for the only touchdown of the day by both teams.  The Colts won the game 19-9 and improved to 3-2 on the season.  With the Chiefs loss they were not longer an undefeated team in the NFL.
Question: How many points were the Colts ahead by at halftime?
Answer: 3