A series of large explosions at a military base in the Equatorial Guinea city of Bata killed at least 20 people on Sunday.
Another 500 people were injured in the blasts.
President Teodoro Obiang Nguema said the explosions were the result of negligence related to the use of dynamite.
In a statement carried on national television, Obiang called for international support in the recovery effort, adding: “I translate all my support to the people who are affected.”
Television station TVGE showed teams pulling people from piles of rubble, some of whom were carried away wrapped in bed sheets.
Pick-up trucks filled with survivors, including children, drove up to the front of a local hospital.
Inside, wards were overwhelmed with the wounded, many covered in blood. Some lay on the floor or on tables, awaiting attention.
TVGE called on people to donate blood and said hospitals in the Central African nation were full.
In the blast area on Sunday, iron roofs were ripped off houses and lay twisted amid the rubble. Only a wall or two remained of most residences.
In the immediate aftermath, people ran in all directions, many of them dazed and screaming.
A column of smoke reached into the sky and around its base firefighters sought to put out the blaze.
“Following developments in Equatorial Guinea with concern after the explosions in the city of Bata,” Spanish Foreign Minister Arancha Gonzalez Laya said on Twitter.
The Spanish Embassy in Malabo said Spanish nationals should stay in their homes.
The blasts come as Equatorial Guinea, an oil producer, is suffering a double economic shock because of the coronavirus pandemic and a drop in the price of crude, which provides around three-quarters of state revenue.
The former Spanish colony has been run by Obiang, Africa’s longest-serving leader, since 1979 when he staged a bloody military coup and ousted his uncle, who was later executed.
Critics point out that Obiang and his family enjoy lavish wealth while the majority of the population lives in poverty.