PROVIDENCE, R.I. (AP) — The investigation into the Brown University mass shooting has dragged on for more than four days with no named suspect, motive, weapon, or even a clear image of the assailant’s face that might help bring them to justice.

Investigators have been hobbled by the lack of clear eyewitness accounts of the shooter and few, if any, cameras in the wing of the building where the attack happened. Despite these difficulties, frustration was mounting Wednesday over the lack of progress.

The attack on Saturday killed two students and wounded nine others, who were studying for a final in a classroom when the gunman opened fire. Ella Cook, 19, and MukhammadAziz Umurzokov, 18, were killed, with others injured varying in condition.

Initial investigations showed confusion, with authorities detaining a person of interest but later releasing them. Brown University faced criticism for the lack of campus video footage of the attack, leading to calls for more extensive security measures. The Ivy League school has a total of 1,200 cameras on campus, but the specific area of the shooting seems poorly monitored.

As the investigation continues, police are asking the community for any potential video evidence leading up to the incident, while also discouraging rampant speculation regarding possible suspects among students. We still don’t know why it happened or who was behind it, a police spokesperson stated as they urged the public to remain vigilant.