Officials said the man did not appear to be targeting Trump or others involved in the trial
The country declared a week of national mourning after what it called a "tragic drama" at a concert by the Guinean rap group Instinct Killers, BBC reported.
The concert took place Tuesday evening on a beach in Ratoma in the capital.
The authorities were "shocked by the tragic drama caused by mass movements at a cultural event," a president's office statement said.
Hospital sources said there were 13 girls among 24 people the dead, the report said.