Ms. Johnson Sirleaf has made no public statement since the start of the quarantine and the fatal shooting of a 15-year-old West Point boy, Shakie Kamara, who was caught in a battle between soldiers and men trying to break out of the quarantine zone.

During her visit to West Point, she apologized to his family and looked at those calling for help with sympathy in her eyes, saying little. Walking several feet behind her, a man in a checkered shirt pulled out Liberian dollar bills from a backpack with his gloved hand and tossed the money to the loudest protesters. The money silenced their criticism but immediately set off fistfights.

A Toyota Land Cruiser took the president out of West Point. Her guards and entourage followed on foot, tossing their used gloves on the ground on their way out.

An Explosive Outbreak

No one knows yet why Ebola has succeeded in spreading at such an alarming rate here in the capital. Ebola has reached the capital cities of Freetown, Sierra Leone, and Conakry, Guinea — the two other West African nations most affected by the current outbreak — but the disease has been more effectively contained.

The first cases in Monrovia were reported only in June. Infections have multiplied quickly here in recent weeks, illustrating the speed with which Ebola can spread in a major urban area. The county containing Monrovia quickly registered the nation’s biggest death toll — now 274 deaths out of a national total of 754, according to the Ministry of Health.

“The Conakry outbreaks have been very small, and they haven’t exploded in Freetown,” said Dr. Armand Sprecher, an Ebola expert for Doctors Without Borders here. “So something is different in Monrovia. It’s something in the disease transmission behaviors in Monrovia that has done this. That’s my guess. We’ve never seen this kind of explosion in an urban environment before.”

Others point to a political system long dominated by an elite out of touch with the population and more focused on jockeying for power. Politicians, including members of the president’s own party, publicly expressed doubts about the extent of the outbreak and even accused her administration of exaggerating it to collect money from international donors.