No one was injured in the incident, SP Ramesh Singh said.
At least five heavily armed men entered the Virgo cement factory at Damas at around 2 AM through the second gate and asked the security personnel in the sentry post to open the main gate door, the SP told PTI.
After they exploded one crude bomb inside the sentry post causing partial damage, another crude bomb was lobbed in the open place before escaping, Singh said.