And another piece was Goulart's civilian base, of course.

20 to 60 ECEME officers entered the Palace to protect Castelo Branco. This alarmed the legalists, who brought reinforcements. After 15:15 civilians were evacuated. The Mechanized Recon Regiment and 2nd Tank Battalion parked tanks on the avenue, blocking the main entrance. There were Presidential Guard and AA elements in the courtyard. Army Police flooded the lower levels.
It was a tense standoff. Legalists controlled the exterior and up to the 4th level. Rebels were on the 5th to the 8th level. The 9th and 10th levels were legalist again and prepared to fight the rebels going up. In turn, the rebels prepared to fight the legalists going up. Elevators were shut down and passages blocked. The rebels were on the disadvantage, some thought the Army Police would force them out with bazookas at night.

Âncora was two staircases above Castelo Branco. He had on his hands an order to imprison him at the Laje Fort. All he had to do was give it. So he did, at 18:00. Castelo Branco had left the building, completely unharmed, at 16:00. It is very possible Âncora deliberately stalled the order until its target could leave.
Castelo Branco and Costa e Silva fled into hiding places, from where they continued their work through telephone lines.

ECEME was paranoid about an armored attack and prepared 60 molotov cocktails. However after 17:00, with Mourão Filho officially proclaiming his uprising, they chose to keep a low profile, releasing prisoners, keeping lights out and resuming classes.