Loading Icon Image while saving record

Apex Class for Loading Image

public class actionStatusImage {
    public Pagereference save(){
        return null;
    }
}

Visualforce for Loading Icon

<apex:page controller="actionStatusImage" tabStyle="Account">
    <apex:form id="formId">
        <apex:pageBlock id="pgBlckId" title="Loading Image">
            <apex:pageBlockButtons >
                <apex:commandButton action="{!save}" value="Save" reRender="pgBlckId" status="actStatusId"/>
                <apex:actionStatus id="actStatusId" >
                    <apex:facet name="start" >
                      <img src="/img/loading.gif" />                    
                    </apex:facet>
                </apex:actionStatus>
            </apex:pageBlockButtons>
        </apex:pageBlock>
    </apex:form>
</apex:page>