The attack claimed the lives of seven people, including one police conscript, and left four citizens wounded.
One attacker was shot dead by security forces, the sources and the state-run news agency Mena reported.
According to the statement, attackers opened fire at a household appliances shop, then headed to the church, where they attempted to trespass the church's perimeter security.
Friday's attack took place as Egyptian Coptic Christians, who make up 10 percent of the country's 93 million population, brace to celebrate their Christmas on 7 January. President Abdel-Fattah el-Sissi has personally chaired meetings with his top security chiefs in recent days to discuss security during New Year's Eve and the Orthodox Christmas.
A gunman opened fire on a church south of Cairo on Friday, killing at least nine people before policemen shot him dead, officials and state media said.
Two men on a motorcycle opened fire and tried to storm the Mar Mina church in Helwan City on Friday, which led to a shootout between the attackers and security officers, according to Egypt's Health Ministry spokesman. Three officers were killed in the ensuing gun battle, along with one of the terrorists.
Z & Beyonce Appear To Confess Everything In Dramatic 'Family Feud' Teaser
Throughout the trailer , the scenes cut from the church to a love scene between an unidentified man and woman. It's like I remember my father saying when I was a little girl: "'Nobody wins when the family feuds '".
Earlier, security officials who spoke on condition of anonymity said two police were killed.
Egypt's Interior Ministry referred to only one, but the Coptic Orthodox church mentioned "gunmen".
Also, the Italian Embassy in Egypt strongly condemned Friday's heinous attack in Helwan.
Samir Gerges, a witness, said people inside the church closed the gates when the shootout began but bullets from the gunfire still entered the building. The officials requested anonymity because they were not authorized to brief the media.
Earlier, an Al Arabiya reporter on the ground said that three policemen were killed at the scene.
Police later cordoned off the crime scene as onlookers crowded around the church, while a forensics team combed the area.