Generally, an injunction cannot be granted without hearing the other side. But there is an exemption to this under Section 94 r/w
Order 39, rule 3 of Civil Procedure Code- when there is an irreparable or serious mischief or when refusing ex parte injunction would be a greater injustice.

Generally court prefers to hear both sides before granting an injunction, but an exception is made if there appears a risk of irreparable harm, the court can grant an ex-parte injunction under Order 39 Rule 3 which provides if the notice would cause unnecessary delay or the principal of greater injustice is used, assessing if not doing so will cause greater injustice to the asking party, temporary injunction, also called restraining order can be granted.