Three separate explosions disrupted the peace in Nepal’s capital Kathmandu, killing at least four and leaving 7 others injured according to police sources.

The deadly blasts went off last Sunday as panic ensued. According to authorities, two explosions took place in the capital’s center while the other two on the outskirts.

Police claim that crude or improvised explosives triggered the blasts.

An official suspects that a Maoist splinter group was responsible for the explosions after their flyers were found near the area. The group held a nationwide strike in protest of their cadre’s death after a police encounter that happened over a week before. The incidents came on the eve of the protest.

Police implicated the same group in another Kathmandu explosion that killed one civilian last February.

According to police officer Shyam Lal Gyawali, three of the victims died “on the spot” while the fourth died at the hospital while undergoing medical treatment.

The initial explosion killed one person in the Ghattekulo residential area. Three other people were killed in the second blast that happened in the Sukedhara area. The third blast injured two more people in the Thankot area of the capital. All of the seven injured were hospitalized.

17-year-old student Govinda Bhandari told Reuters news agency in an interview: “I heard a big noise and rushed to the spot to find the walls of a house had developed cracks due to the impact of the blast.”

Security forces have restricted the blast locations while investigations are currently ongoing. The government banned activities of the suspected Maoist splinter group as they were outlawed following the deadly incident.