The Egyptian government has blamed the Hasm group for carrying out a terrorist attack at Cairo's main cancer hospital after an explosion on Sunday night killed 20 people and injured 47.
The Interior Ministry has said the explosion occurred after a speeding car travelling against the traffic filled with explosives collided with three other cars outside the National Cancer Institute.
Egyptian President Abdel Fattah Al-Sisi has said that Egypt will defeat "brutal terrorism" and "pull out terrorism by the roots."
Authorities have now accused the Hasm group, which they say is a wing of the Muslim Brotherhood, and have announced the arrest of one member.
The Interior Ministry says that most of the militants responsible were killed in an "exchange of fire" in the desert areas of Giza and that a vehicle full of explosives was stolen in Menoufiya several months ago.
Most political prisoners in Egypt are blamed for part of the Muslim Brotherhood, whether they are or not. The organisation was made illegal in 2013.
Timothy Kaldas, a non-resident fellow at the Tahrir Institute for Middle East Policy, told Al-Jazeera that the Egyptian authorities were unlikely to have enough information to be sure that Hasm carried out the attack: "The Hasm group has been largely inactive for the last couple of years. You hear from them occasionally but they haven't been nearly as active as they have been in the past. It would be surprising to see them re-emerge on the scene."
It is also just possible that the government chose to blame them initially because the government sees them as an extension of the Muslim Brotherhood's leadership, and so it's just a way for them to pin the blame on the Brotherhood from the outset.
"It's very possible that this could have been a different group."
The Egyptian government has been criticised for having a disproportionate reaction to terror attacks and carrying out severe human rights abuses across the country in the name of the war on terror.
In 2015 authorities blamed the Muslim Brotherhood and Hamas after a car bomb hit and killed top prosecutor Hisham Barakat. Three years later authorities announced that 14 members of the Brotherhood had confessed to the killing.
After Barakat's death the government introduced new legislation that imposed the death penalty or life imprisonment on anyone found to be establishing, organisation or financing a terror group.
At the end of 2018 Egypt's highest appellate court upheld the death sentence against nine people it accused of killing Barakat, including Ahmed Wahdan who was forcibly disappeared for a month before being taken to Scorpion Prison.
In Sinai Egypt is conducting a war on terror and in the process has demolished thousands of houses, razed farmland to the ground and displaced 100,000 people.