Chilling video shows a suspected Sri Lanka suicide bomber calmly patting a young girl’s head on his way into church — seconds before a blast killed at least 122 worshipers.

Security camera footage shows the young-looking man, dressed in dark pants and a light blue shirt, casually strolling toward St. Sebastian’s church with a heavy camping-style bag on his back.

As he first crosses a courtyard, he pauses to let by a man with a young girl — seemingly even giving the young girl a friendly pat as she passes.

He then walks in the middle entrance of the church, one of three targeted in the coordinated terror attacks and standing-room-only with worshipers for Easter Sunday Mass.

Passing parishioners standing on the edges, he finally heads down a pew toward the center of the church — where the video cuts before the explosion.

The church has since given police the full footage of the blast, according to CNN.

St. Sebastian’s was one of three churches struck at the same time as three popular hotels in the atrocity that claimed at least 321 lives in total — including at least four Americans — and injuring 500 others.

Sri Lankan officials said at least 40 suspects have been arrested for the attack that officials believe was “retaliation” for mosque shootings in New Zealand.