Taylor Kinney Is All Smiles on Chicago Fire Set After Split from Lady Gaga

Taylor Kinney is beating the breakup blues by getting back to work.

On Thursday, the star's Chicago Fire co-star Kara Killmer tweeted a photo from set that shows Kinney mugging for the camera while in costume for his role as Kelly Severide.

"We're baaaaack!!!" Killmer, who plays Sylvie Brett on NBC's hit show (which returns in October), captioned the fun selfie.

Earlier this week, PEOPLE confirmed Kinney and longtime love Lady Gaga ended their engagement after five years together, but the split may not be for good.

RELATED VIDEO: Lady Gaga: 'Taylor and I Have Always Believed We Are Soulmates'

"Taylor and I have always believed we are soul mates. Just like all couples we have ups and downs, and we have been taking a break," the singer wrote in an emotional post on Instagram. "We are both ambitious artists, hoping to work through long-distance and complicated schedules to continue the simple love we have always shared. Please root us on. We're just like everybody else and we really love each other."

The "Bad Romance" singer's rep also told PEOPLE the duo were "taking a break," while a source added that "they both love each other very much and they want it to work. It's just been tough with the long distance."

Kinney proposed to Gaga on Valentine's Day 2015 with a heart-shaped Lorraine Schwartz engagement ring after four years of dating.