An explosive charge went off on Monday outside a court complex in downtown Cairo - for which a shadowy group has claimed responsibility - amid conflicting reports of casualties.A group calling itself "The Revolutionary Punishment" said on Twitter that its members had planted an explosive charge that targeted a police patrol outside central Cairo's High Court of Justice.According to the group, the bombing left at least four policemen wounded, including some that sustained critical injuries.Earlier in the day, a security source told The Anadolu Agency that at least one person had been killed and three others injured.Health Ministry spokesman Hossam Abdel-Ghaffar, however, told AA that nearly nine people had been injured but didn't mention any fatalities.Bombings have become a common occurrence in Egypt since Mohamed Morsi - Egypt's first democratically elected president - was ousted by the army in mid-2013.The government accuses Morsi's Muslim Brotherhood group of carrying out the attacks.The Brotherhood, for its part, denies the allegations, saying it is committed to purely peaceful activism.