Per Boston 25 News, police were called to the home at 6:18 p.m. on Monday and remained there until approximately 11 p.m.
Gronkowski had been with the Patriots in Minneapolis since last Monday in preparation for Super Bowl LII. He left with his team on Monday, one day after the Philadelphia Eagles posted a 41-33 victory.
"There were items stolen," Foxborough Police Chief William Baker told reporters Tuesday morning. "We're not going to release the nature of the items stolen.
"Obviously the people who committed the theft know what was stolen. It's an investigative advantage for us to know that as well and not share it with the public, so I won't have any further comment on that."
Gronkowski had nine receptions for 116 yards and two touchdowns on Sunday.
The 28-year-old had a team-high 69 catches for 1,084 yards and eight touchdowns this season.
Gronkowski set the NFL single-season record for touchdowns (18 -- 17 receiving, one rushing) and receiving yards (1,327) by a tight end in 2011. He also became the first player at the position to lead the conference in scoring with 108 points.
The five-time Pro Bowl selection has collected 474 career receptions for 7,179 yards and 76 touchdowns in 102 regular-season games. His contract runs through the 2019 season.