A gunman opened fire on Muslim worshippers who were performing their Friday night prayers in the central Sudanese city of Omdurman, killing 20 people and injuring at least 30 others.
The gunman was then shot and killed by police.
The attacker, identified as Abbas al-Baker Abbas, was a member of an Islamic militant group called Takfir wal Hijra.
The motive of the shooting was not immediately known, though there is speculation that it could be a result of rivalry between Muslim sects in Sudan.
The massacre took place in a suburban mosque in central Sudan on Friday night.
The attacker, Abbas al-Baker Abbas, walked into the grounds of the mosque and began firing an automatic rifle through a window at worshippers.
Twenty were killed and 33 others were wounded.
After the gunman refused to surrender, four police units rushed inside and shot him .
The motive of the deadly attack isn't yet known.
But the militant group, which the gunman is associated with, has been implicated in past attacks on rival Muslim sects.
Today, the Sudanese President visited the site of the shooting with police and state officials.
People gathered outside, where the President then offered words of comfort to the bereaved, and called on them to be patient.
He said it was a sad irony that the Sudanese government had only recently drawn up plans in an attempt to stop such violent religious fanatasicm and that new, tougher laws, against those who attack the beliefs of others, had just been passed.