Three explosions were heard in Zimbabwe's capital Harare on Wednesday as military vehicles were seen in streets.
The explosion comes after an army commander threatened to step in to calm political tensions over 93-year-old President Robert Mugabe's possible successor.
According to eyewitnesses, gunfire erupted near Mugabe's private residence in Harare in the early hours of Wednesday.
Mugabe's ZANU-PF party accused army chief General Constantino Chiwenga on Tuesday of "treasonable conduct".
The public dispute has presented a major test for Mugabe, who is in increasingly frail health. Chiwenga had demanded that Mugabe stop purges of senior party figures, including vice president Emmerson Mnangagwa, who was dismissed last week.
ZANU-PF said Chiwenga's stance was "clearly calculated to disturb national peace... and suggests treasonable conduct on his part as this was meant to incite insurrection".
The US embassy in Zimbabwe has told American citizens in the country to 'shelter in place'.
The UK embassy in Harare also urged its citizens in the country to stay indoor during the uncertain situation.
Tensions have been building in Zimbabwe since Emmerson Mnangagwa, a powerful figure in the ruling Zanu-PF party, fled to South Africa last week.
Meanwhile, Zimbabwe army said once mission accomplished, 'situation will return to normalcy'.
Zimbabwean soldiers and armoured vehicles have blocked roads to the main government offices, parliament and the courts in central Harare.