Sean, 45, and Ruffalo, 38, were amongst family and friends paying tribute to the 40-year-old RESERVOIR DOGS star, who was found dead in his Santa Monica, California, apartment on 24 January (06), at the Holy Cross Cemetery in Culver City, California.
The New York Daily News reported Sean was furious to see a paparazzo interrupting his family's grieving and his anger propelled Ruffalo to snatch the memory card from the snapper's digital camera.
News site TMZ.com reports an unnamed photographer lodged a criminal complaint against Ruffalo at Culver City Police Department on Saturday afternoon.
A spokeswoman for Sean said she wasn't aware of any altercation, saying, "The Penn family, with the loving support of family and longtime friends, buried their youngest son and brother, Chris, today at a private service. I have no knowledge of an incident and have no intention of disturbing the family at this time."
During the funeral, Sean read a eulogy to his late brother, saying, "I had a little brother. And for any brother who goes over to the other side with our father, into the cosmos, I will follow if they let me."