One person has been killed and at least four people have been injured after a bomb was thrown at a bus in outside the Azhar University in Cairo Thursday morning.

The site of the explosion has been cordoned off and is being investigated by police, according to Egyptian media reports.  

The apparent terrorist attack comes just one day after the interim Egyptian government blacklisted the Muslim Brotherhood as a terrorist organization, following a deadly attack on a security installation on Tuesday.

That attack was claimed by a Salafi group, Ansar Bayt al-Maqdis, but Egyptian interim authorities have longed accused the Muslim Brotherhood of playing an active role in fomenting deadly violence in response to the ouster of Islamist president Mohammed Morsi – charges the Brotherhood denies.

Thursday’s attack is likely to inflame tensions further, as Muslim Brotherhood members vow to continue their demonstrations in protest of Morsi’s ouster.