Three Palestinians were killed and four were wounded in a blast in the Gaza Strip Wednesday.

The incident occurred in the southern city of Khan Younis, in a building associated with the Izz ad-Din al-Qassam Brigade — the armed wing of Hamas.

The details of the incident were unclear, Ashraf al-Qidra, a spokesman for Gaza’s Health Ministry, told the Palestinian Ma’an news agency.

He added that two of the men were pronounced dead at the scene, while the third was critically injured and died en route to the hospital.

The four injured were treated for shrapnel wounds.