SAN ANTONIO -- North Side Independent School District officials announced on Thursday that three schools will be closed Tuesday due to the mulch fire in Helotes.

The schools include O'Connor High School, Helotes Elementary and Krueger Elementary, said NISD Supeintendent John Folks.

The three schools are within a two-mile radius of the mulch fire that has been burning since Christmas Day.

On Saturday, a contractor plans to aggressively attack the fire, which is expected to create extreme smoky conditions that day, Sunday and Monday, Folks said.

Classes were already canceled Monday due to the Martin Luther King holiday.

Folks said that he will continue to monitor the situation with officials of the Texas Commission of Environmental Quality on Monday to determine if other schools will need to be closed.

Those schools include Beard, Steubing, Wanke, Braun Station, Nichols and Brauchle elementary and Stinson Middle School.

All weekend athletic activities at the three schools were also canceled because of the potential health risk.

The health consequences of the fire have already affected seven O'Connor High School students, who have temporarily transferred to other schools because of acute asthma symptoms.