Police in Rio de Janeiro detained four people on Thursday on suspicion of sparking a fire inside Olympic Park, the main venue cluster for the Rio 2016 Games.
The blaze occurred at 3 p.m. local time, partially damaging a storage container outside the Olympic tennis centre, the Globo newspaper reported.
It is understood nobody was injured in the incident.
The fire occurred just hours after construction workers staged a protest over alleged unpaid wages, Xinhua news agency reported.
Authorities said the fire did not damage any Olympic facilities.
Located in Rio's western neighbourhood of Barra da Tijuca, Olympic Park comprises nine venues that will host 16 Olympic and nine Paralympic events.
