He said security agencies are treating the matter with seriousness given the sensitive nature of the location and the timing of the incident.
According to preliminary reports, the attack occurred as worshippers had gathered for prayers.
Witnesses said a group of individuals stormed the mosque and began assaulting people inside, causing panic and confusion.
Some victims sustained injuries and were treated at nearby medical facilities.
Police officers responded shortly after receiving distress calls from members of the public. The area was cordoned off as forensic teams began collecting evidence.
Detectives are now reviewing CCTV footage from surrounding buildings and speaking to witnesses in a bid to track down the attackers.
Amin said investigators are exploring all possible angles, including criminal motives and extremist links.
“At this stage, we are not ruling out anything, including terrorism,” he stated, while urging the public to remain calm as investigations continue.
He emphasized that it would be premature to draw conclusions before all facts are established.
The DCI boss also called on anyone with information that could assist the investigation to come forward and cooperate with authorities.
The attack has sparked concern among residents and religious leaders in Nairobi.
Community elders have condemned the violence, describing it as unacceptable and contrary to the country’s tradition of religious tolerance.
They have appealed for unity and restraint as security agencies carry out their work.
Waiyaki Way is one of the busiest roads in the capital, linking the city centre to several residential and commercial areas.
An incident of this nature has therefore raised alarm among many Kenyans who are worried about public safety.
Security has since been heightened around places of worship in the area as a precautionary measure.
Patrols have been intensified, and officers have been instructed to remain alert to any suspicious activity.
Kenya has in the past faced threats linked to extremist groups, which is why authorities are taking no chances.
However, officials insist that investigations must be allowed to proceed without speculation.