Costa Rican authorities issued an emergency alert on Thursday after ash from the erupting Turrialba volcano reached the capital San Jose and beyond.

The alert came after a series of eruptions late Wednesday and early Thursday. The National Emergency Commission also ordered the closure of the national park around the volcano.

In a statement, authorities said 11 people had been evacuated to temporary shelters around the town of Santa Cruz de Turrialba.

Other people whose communities were threatened by ash also gathered at the town.

Residents of San Jose, about 35 kilometers (20 miles) from the volcano reported smelling sulfur, while falling ash was seen as far away as Ciudad Colon, about 50 kilometers (30 miles) away.

Geologist Carlos Martinez from the National Seismological Network, said the eruptions were coming from a new fissure that appeared near the crater a few years ago.

He said the biggest eruption came at dawn on Thursday, when a column of smoke and flame about 300 meters (1,000 feet) high forced observing scientists to retreat to safety.

Authorities are also monitoring two other volcanoes -- Rincon de la Vieja in the northwest, and Poas, in the country's center.