The kids of late NYPD Det. Steven McDonald and ​recently ​slain FDNY EMT Yadira Arroyo threw out the ceremonial first pitches at Opening Day at Citi Field on Monday.

Mets fans gave rousing cheers to NYPD Sgt. Conor McDonald, 29, and Arroyo’s son Kenneth Robles, 19, who threw baseballs, ahead of the Mets sea​​son-opening 6-0 win over the Atlanta Braves.

McDonald died in January after he was shot on the job and paralyzed in 1986.

Arroyo was killed in March​, run over by a man who had stolen her ambulance.