Police in Lyon, France, arrested a 48-year-old Briton, whose name was not reported, for allegedly killing his two children at the center of a custody dispute with his ex-wife, Britain's Sunday Telegraph reported.
The mother, whose name was not reported, bumped into her ex-husband as he was leaving the lobby of his apartment building while wearing roller skates and covered in blood.
She then found her two children -- ages 5 and 10 -- dead in his apartment.
"It was the first time since the divorce that the man was allowed to be alone with the children," a judicial source told the Telegraph.
He said a knife, "which may have been used for the murders," was found in the apartment.
The man allegedly had problems with alcohol and physically abused his ex-wife in the past, the newspaper said.