To identify those at risk in case of a fire, you must look at where your employees are working. Also, consider who else may be at risk, e.g. customers and visitors, and where they're likely to be found.
You must consider those who may be especially at risk, such as:
In larger buildings used extensively by the public, you may need to get professional advice.
You must pay particular attention to employees who have special needs, such as those with a disability. During your assessment, you may want to discuss their individual needs with them.
Disabled people may react differently to a fire warning, especially if they have mobility issues. Therefore, you must also provide a safe means for them to exit if there is a fire. You must make other reasonable adjustments to ensure that they're not put at a disadvantage when compared to employees without disabilities.
Similarly, you should also consider others with special needs, such as young children and the elderly.