Workers erect floral installations at the scene of Sunday's crash of Ethiopian Airlines Boeing 737 Max 8, which killed all 157 on board, near Bishoftu, Ethiopia. (Mulugeta Ayene/AP)

It’s been three days since an Ethiopian Airlines jet crashed en route from Addis Ababa to Nairobi, killing all 157 people on board. The victims included professors, humanitarians and tourists from more than 30 countries.

Since their tragic deaths, those mourning them have expressed an outpouring of grief, holding vigils in their home countries and sharing eloquent tributes to them online. In Ethiopia, as investigators work to determine the cause of the crash, relatives and friends of the victims gathered at the site of the crash, leaving flowers and offering prayers.

For those grieving, their communal anguish shares the thread of a single question: Why?

Photographer Mulugeta Ayene has documented the aftermath of the crash for the Associated Press from Ethiopia.

Officials from China's Aviation Industry Corp. bow next to an offering of fruit, bread rolls and a plastic container of Ethiopian injera, a fermented sourdough flatbread, placed next to incense sticks at the crash scene. (Mulugeta Ayene/AP)

Family members grieve at the crash scene. Passengers and crew aboard the plane were from more than 30 nations. (Mulugeta Ayene/AP)

Investigators from Israel examine wreckage at the scene. (Mulugeta Ayene/AP)

Flowers are left at the scene. Because of the active investigation, family members could not enter the crash site. (Mulugeta Ayene/AP)

A grieving relative is held back by others at the crash site. (Mulugeta Ayene/AP)

A family member places a photo amid flowers at the crash site. (Mulugeta Ayene/AP)

Workers walk past flowers laid at the scene. (Mulugeta Ayene/AP)

Under the instruction of investigators, nurses walk to collect materials at the crash site. (Mulugeta Ayene/AP)